open
Noun pluralopens
Pluralopens
- 1To move a door, lid, cover or seal so that something is no longer shut or sealed, or to become no longer shut, giving access or a way through.
Customs officers open suspicious parcels for inspection.
The vacuum-sealed bag opens with a soft hiss.
UsageOpen a door, window, box or bottle, but turn on a light (not
incorrect: open the light). - 2To make or become ready and available to customers, visitors or users, whether for the day or for the first time.
The company plans to open three new branches downtown.
The restaurant opens for dinner only on weekends.
UsageThe shop opens at nine for the action; the shop is open for the state.
Similarlaunch, start (entry), establish
Oppositeclose
- 3Not covered or sealed, with a gap or opening that shows what is inside.
The jar sat open on the counter, its lid resting beside it.
Someone had left the bag of chips open, and now they're all stale.
UsageFor a state, use open: the window is open. Opened describes the action: someone opened the jar.
- 4Ready for business, or ready to admit customers, visitors or the public.
The gardens remain open to the public from dawn until dusk.
The new gallery is open to anyone who books a slot in advance.
UsageCommon in open to the public and declare something open.
Similaraccessible
Note
The ceremonial side of the word: "I hereby declare this fete open" is the set formula an official speaks. The verb describes the same act in the passive: the new library was opened by a local author. An open day is a fixed date on which a school or similar place lets visitors in.
Checked 31 Oct 2026 · 1 fact
- The quoted wording is an illustrative ceremonial formula, with no named speaker or historical occasion attributed. en.wiktionary.org
- 5
- 6To load a file or document, or start a program or app, so that it can be viewed, edited or used.
Double-click the icon to open the spreadsheet.
Large files open slowly on older machines.
UsageOpen a file, document or app; when you finish, close it.
Oppositeclose
Note
A computing sense whose object can be the thing you work on, such as a file or a document, or the program itself. Opening a file connects you to it. That is why a file can refuse to open while someone else is editing it: the resource is already in use. A file is said to be open for as long as that connection lasts.
Checked 31 Oct 2026 · 4 facts
- Programs and apps can also be opened. support.apple.com
- Opening a file establishes a connection to it. sourceware.org
- A file can fail to open because another user or process is using it. learn.microsoft.com
- A file remains open while its connection persists. sourceware.org
- 7
- 8Available to the public; not hidden or restricted from general view.
City budget records are open to anyone who files a request.
The hearing was deliberately kept open so the community could observe.
UsageOften open to + who may see it: open to anyone. Also in an open letter.
Similarpublic, accessible, available
Oppositeclosed, private, restricted, confidential
Note
Best known from the open letter. It is usually addressed to one person, such as a governor, but published, often in a newspaper, so that everyone reads it. The address is a device, and the real audience is the public. Lawyers use the word differently in litigation, where an open letter is one that may be referred to at trial.
Checked 3 Nov 2026 · 3 facts
- An open letter is intended for public readership despite being addressed to an individual. globalencryption.org
- Open letters are commonly made public through newspapers and other media. en.wikipedia.org
- In litigation, open correspondence may be referred to in court. weightmans.com
- 9Of a space, free of objects and things that block the way.
The cattle wandered freely across the open plain.
Once the movers took out the furniture, the whole floor was open for dancing.
UsageOften in open country, the open road and an open space.
Similarclear, empty, unobstructed
Note
Space with nothing in the way: an open room, an open area among huts, open country beyond the forest. Kenneth Grahame's The Wind in the Willows (1908) gives the famous pairing "the open road, the dusty highway," where the adjective carries freedom as well as emptiness. The noun phrase "the open" is this same idea turned into a place.
Checked 31 Oct 2026 · 3 facts
- Kenneth Grahame wrote The Wind in the Willows. en.wikisource.org
- The Wind in the Willows was first published in 1908. en.wikisource.org
- The quoted words occur in the novel, spoken by Toad. en.wikisource.org
- 10Willing to consider new ideas, suggestions, or experiences without resistance.
The director remained open to criticism throughout the rehearsals.
Negotiators who stay open to compromise tend to reach a deal faster.
UsageFollowed by to + noun or -ing: open to ideas, open to using the bus. Compare open to attack, meaning exposed.
Similarreceptive, amenable, responsive
Oppositeresistant, unreceptive
- 11Made public and usable under a free license, with no proprietary components.
Because the file format is an open standard, any company can build software that reads it.
The university publishes its lecture notes and videos as open courseware.
UsageOften in open source, open standard and open access.
Similarfree
Oppositeproprietary, closed
Note
In computing and education the word is about rights as well as access: anyone can read an open textbook, and its license also lets people copy, adapt and share it. An open file format has a published specification that anyone may implement. The usual contrast is proprietary, privately owned and controlled. In massive open online courses, though, open often means free to join rather than openly licensed.
Checked 31 Oct 2026 · 4 facts
- Open textbooks provide access and permission to copy, adapt and share, subject to their licenses. open.umn.edu
- Open formats concern publicly documented, implementable specifications; permission to modify the specification is not guaranteed. OpenDocument's specification restricts modification, with specified exceptions. docs.oasis-open.org
- The contrast is proprietary, which restricts users' freedoms to copy, modify or redistribute; ownership by one company is not its defining condition. en.wikipedia.org
- The word appears in the name, but MOOCs need not openly license their content. unesco.org
- 12
- 13Of a person, not hiding their feelings or opinions; honest and candid.
The new manager is remarkably open about the company's problems.
Being open with strangers came naturally to her.
UsageFollowed by about a topic and with a person: open about her plans, open with her friends.
Similarfrank, candid, honest, forthcoming
Oppositesecretive, guarded, reserved
Note
Said of a person's character rather than of an act: in Shakespeare's Othello, the Moor is "of a free and open nature," and Addison calls the French "open, familiar, and talkative." The modern construction adds about, as in open about their sexuality. Compare the "overt" meaning, which describes deeds done in plain sight. This one describes someone who keeps nothing back.
Checked 31 Oct 2026 · 2 facts
- Shakespeare wrote Othello, in which Iago describes Othello, the Moor, as being "of a free and open nature." gutenberg.org
- Joseph Addison describes the French as "open, familiar, and talkative." en.wiktionary.org
- 14Unobstructed, so that something can pass through or along it.
Crews worked through the night to keep the mountain pass open.
With the channel open, ships could finally reach the harbor.
UsageOften with keep, stay, or remain (keep the pass open); the opposite is closed.
Similarclear, passable, unobstructed
Oppositeclosed, blocked, impassable
Note
The physical sense at the root of the rest: Old English open, from Germanic *upanaz and ultimately an Indo-European root meaning "up from under, over." Here the point is passage: a door you can walk through, a channel cleared of ice.
Checked 2 Nov 2026 · 2 facts
- English open descends from Old English open and Proto-Germanic *upanaz. en.wiktionary.org
- The word ultimately derives from an Indo-European root glossed "up from under, over." en.wiktionary.org
- 15
- 16Not yet settled, decided, or determined; still under consideration.
The committee kept the proposal open pending further evidence.
Whether the museum will expand is still an open question.
UsageCommon in an open question, keep your options open and leave it open.
Similarunresolved, undecided, unsettled, pending
- 17An area of unobstructed, exposed space, away from shelter or cover.
The soldiers were caught in the open as enemy troops fired from the ridge.
Out in the open, the wind hit them with full force.
UsageWith the: in the open, out in the open.
Note
The phrase names exposure more than space, as with a lawnmower left to the rain or a deer avoiding ground where hunters can see it. Its figurative twin, "public view", works the same way: secrets are brought into the open.
- 18Of a tournament or competition, allowing anyone to enter, especially regardless of amateur or professional standing.
The golf event is open to anyone who clears the qualifying score.
Because the tournament was open, club players got to face national champions.
UsageBefore the noun (an open tournament) or with to: open to all comers.
Note
A sports term whose force lies in who may enter. The defining line was originally the one between professionals and amateurs: an open event let both compete in the same field. The label survives even where that distinction matters less.
Checked 2 Nov 2026 · 1 fact
- The sports sense originally concerned admitting both professionals and amateurs to the same competition. en.wikipedia.org
- 19A sporting event in which anybody can compete, especially regardless of amateur or professional status.
The tennis open drew a field of seasoned pros and rising amateurs.
Qualifying rounds for the open ran all week before the main draw.
UsageIn names it is capitalized and keeps the: the Australian Open.
Note
The noun grew from the sports adjective: an open tournament becomes simply an open.
Checked 2 Nov 2026 · 1 fact
- The sporting noun developed by shortening a phrase containing the sports adjective. en.wiktionary.org
- 20Not concealed; done plainly for all to see.
The two leaders showed open contempt for each other during the debate.
Her support for the cause was open and unmistakable.
UsageOften before words of feeling or conflict: open contempt, open hostility, open warfare.
Similarovert, undisguised, unconcealed, blatant, public
- 21To begin an event or activity as the first performer or act.
Local acts open the concert before the headliner takes the stage.
She opened for a famous comedian during last summer's tour.
UsageOpen a show means going first; open for a star means warming up before them.
Oppositeclose
Note
This is the opening act's verb, and it works with or without an object: a band opens, or an impersonator opens the show.
- 22To establish a new account, file or case, most commonly an account with a bank.
Customers can open a checking account online without visiting a branch.
The agency opened a file on the contractor after the first complaint came in.
Similarstart (entry), create, establish
Oppositeclose
Note
Here opening brings something into existence instead of getting into it: when an agency opens a file on someone, the file is new, whereas opening a document on a computer reaches one that already exists. The natural opposite is close. You open and close a bank account, and investigators open a case, close it, and sometimes reopen it.
Less common meanings
- 23Spread apart rather than drawn together, folded, or contracted.
The peacock's tail stood fully open in a wide fan of feathers.
He laid the newspaper open across the breakfast table.
UsageCommon in with open arms and an open hand.
Note
Here the opening is a spreading out: arms, a hand, a flower, a book laid flat at a page. Dryden's knights are greeted "with open arms," and the phrase keeps both the literal gesture and its warm figurative sense of eager welcome. Applied to cloth, open means loosely woven, with gaps between the threads. It is the opposite of a close or tight weave.
Checked 31 Oct 2026 · 1 fact
- Dryden describes ladies greeting their chosen knights with the quoted words "with open arms" in The Flower and the Leaf. chaucer.fas.harvard.edu
- 24
- 25To make someone or something receptive or susceptible to something, or to become so.
Publishing the emails would open the senator to charges of hypocrisy.
After a year of therapy, he slowly began to open to the possibility of forgiving his father.
UsageFollowed by to: opened him to criticism, opened her to new ideas.
Similarexpose
- 26Resulting from a cut, puncture or other break that leaves an internal part of the body no longer protected by the skin.
The skier was flown to the hospital with an open fracture of the lower leg.
An open wound on the hand can let bacteria into the bloodstream.
UsageCommon in an open wound and an open fracture.
Similarcompound
Oppositeclosed
Note
Medicine sets the word against closed. An open fracture, also called a compound fracture, is one where the skin over the break is torn; a closed fracture leaves the skin intact. The difference matters because exposed tissue can become infected, so open injuries are cleaned and treated with that risk in mind.
Checked 31 Oct 2026 · 6 facts
- Medicine distinguishes open fractures from closed fractures. hopkinsmedicine.org
- An open fracture is also called a compound fracture. my.clevelandclinic.org
- An open fracture involves a skin wound communicating with the broken bone. meshb.nlm.nih.gov
- A closed fracture leaves the skin intact. hopkinsmedicine.org
- Broken skin allows bacteria to enter and cause infection. orthoinfo.org
- Open injuries are cleaned and treated to reduce infection risk. orthoinfo.org
- 27
- 28Of a program or application, especially one with an on-screen interface: running.
Leaving dozens of apps open can slow down an older phone.
The video editor stayed open in the background while he answered emails.
UsageAfter the noun, with have, leave or keep: too many apps open.
Similarrunning
Oppositeclosed
Note
The opposite is closed, and an open program need not be on screen at all, since it may simply be running out of sight and using memory.
Checked 2 Nov 2026 · 1 fact
- An open application can run in the background and use memory without appearing on screen. eng.ox.ac.uk
- 29Liable to be affected by, or vulnerable to, the stated means.
Skipping the audit left the firm open to fraud.
The unguarded flank left the army open to attack.
UsageFollowed by to: open to attack, open to abuse, leave yourself open to criticism.
Similarvulnerable, exposed, susceptible, liable
Oppositeimmune, invulnerable
- 30In team sports, of a player or goal: not guarded or marked by anyone on the opposing team.
The quarterback spotted his tight end wide open in the end zone.
With the goalie out of position, she had an open goal and calmly tapped the ball in.
UsageOften wide open, and players get open by losing their marker.
- 31Having ends that are not joined together; not forming a closed loop.
The bracelet was an open band that slipped over the wrist.
A break in the wiring left the circuit open and the lamp dark.
Oppositeclosed
Note
A shape word with a technical edge: an open curve has two loose ends, like a horseshoe rather than a ring. The same idea explains the open circuit, wiring that does not close back on itself. That is why current cannot flow through an open circuit. The opposite throughout is closed: a closed curve, a closed loop, a closed circuit.
Checked 31 Oct 2026 · 5 facts
- An open curve has separate starting and ending points, unlike a closed curve such as a circle. docs.mcneel.com
- An open circuit has an incomplete conducting path. learninglab.rmit.edu.au
- Current cannot flow around an open circuit because its conducting path is interrupted. webhome.phy.duke.edu
- Closed is the corresponding opposite for curves and loops. en.wikipedia.org
- A closed circuit has a complete conducting path. learninglab.rmit.edu.au
- 32The state of being publicly known or subject to scrutiny; full view.
Years of quiet dealings were dragged into the open by the inquiry.
Bringing the dispute into the open forced both sides to explain themselves.
UsageWith the: into the open, out in the open, bring something into the open.
Similarlight
- 33Describing a relationship or marriage in which the partners agree that each may have romantic or sexual relationships with other people.
After fifteen years of marriage, the couple decided to try an open marriage.
Keeping an open relationship healthy, the therapist said, depends on rules both partners actually accept.
UsageMostly in open marriage and open relationship. For honesty, say partners are open with each other.
Oppositemonogamous, exclusive
- 34Of a door, gate, or lock, not fastened, so it can be opened, though it is still shut.
- 35Of a valve, tap, or similar control, set so that liquid or gas can pass through.
- 36Of a sandwich or similar dish, made with one piece of bread and the filling left uncovered on top.
- 37Of weather or a climate, mild enough that frost and snow do not close roads or rivers.
- 38Of a file, network connection, or similar resource, currently being accessed or in use.
- 39In law, of a settlement offer or letter, made on the record so that it can be shown to the court, unlike a confidential offer.
- 40Freely available to anyone, as with open-access publishing, or following the practices of open science.
- 41Of a game or match, flowing freely, with lots of attacking and space rather than tight, defensive play.
- 42Of an electric circuit or switch, not forming a complete path, so that current cannot flow.
- 43In graph theory, of a walk or path, starting at one vertex and finishing at a different one.
- 44Of a syllable, finishing with a vowel sound and no consonant after it.
- 45In logic, of a formula, having at least one occurrence of a variable not bound by any quantifier.
- 46In topology, of a set, belonging to the chosen family of subsets that gives a space its topological structure.
- 47Of a note on a stringed instrument, sounded on a string that no finger is holding down.
- 48Of a note on a wind instrument, played without covering finger holes, closing keys, or using valves.
- 49Of a vowel, pronounced with the tongue held low and the mouth wide, as in father.
- 50Of a consonant, made by narrowing the mouth passage without shutting it completely, as with f or s.
- 51In programming with macros, describing program text that lies outside the body of the macro being expanded.
- 52Of a compound word, written as separate words with a space, like ice cream, rather than closed up or hyphenated.
- 53Of the face of a golf club, cricket bat or racket, tilted upward or turned outward from straight, rightward for a right-handed player.
- 54In nursing, to fold the covers of a made bed back so a patient can get in.
- 55In card games, to lay down or show the cards one is holding.
- 56To shift into a setting that lets liquid or gas through, as a valve or tap does.
- 57To tilt the face of a golf club, cricket bat or racket upward, or turn it outward from straight, rightward for a right-handed player.
- 58Of a switch or circuit, to break the connection so that current stops.
- 59To switch a light, radio, or other device on.
- 60To be the warm-up act that plays before the headliner.
- 61In cricket, to be one of the pair of batters who start a team's innings.
- 62In poker, to make the first bet in a round of betting.
- 63To change a marriage or relationship so that the partners may also have other partners.
- 64To make something known, or to explain or interpret its meaning.
Unto thee have I opened my cause.
1611, The Holy Bible, King James Version - 65A gap or broken connection in wiring that keeps electricity from getting through.
- 66A single occasion on which something, typically an email, is opened.
Showing meanings only.
More uses
- open relationshipa relationship in which the partners agree they may see other people
Practice
Can you tell the meanings of open apart? Answer 3 quick questions from this page, or write your own sentence and AI will check it.
Origin
The adjective comes from Middle English 'open', from Old English 'open', tracing back through Proto-West Germanic and Proto-Germanic *upanaz to a Proto-Indo-European root meaning 'up from under, over'. It has cognates like Dutch 'open', German 'offen', and Swedish 'öppen', and is related to the word 'up'. The verb derives similarly from Old English 'openian', and the noun comes from the verb, with the sports sense being a shortening of 'open competition'.
Checked 1 Nov 2026 · 6 facts
- The adjective descends through Middle English and Old English open, Proto-West Germanic, and Proto-Germanic *upanaz to a Proto-Indo-European form glossed 'up from under, over'. en.wiktionary.org
- Dutch open, German offen, and Swedish öppen are cognates. en.wiktionary.org
- Open is etymologically related to up. en.wiktionary.org
- The verb descends from Old English openian and ultimately shares the adjective's Germanic ancestry. en.wiktionary.org
- The noun derives from the verb. en.wiktionary.org
- The sports noun is a shortening of open competition. en.wiktionary.org