sure
- 1Confident and free of doubt in one's knowledge or belief.
She felt sure she had met him somewhere before.
The investigators were sure of the cause once the lab results arrived.
UsageSay sure of or sure about something, or sure + a clause: I'm sure she's right.
- 2Certain to act in a particular way or to turn out as expected; also, certain to get or have something, as in sure of a seat.
With this much rain, the river is sure to flood by morning.
A talent like hers is sure to be noticed sooner or later.
UsageSure to + verb predicts an outcome: she is sure to win. Be sure to lock up means don't forget to.
Oppositeunlikely
- 3Used to say yes or agree, either willingly or, depending on tone, reluctantly or without much interest.
"You okay with this plan?" "Sure," she muttered, barely looking up.
"Should we get going now?" "Sure, if we have to."
UsageAdding I guess makes it sound less willing: Sure, I guess.
Note
A yes that can be warm and willing or have all the enthusiasm drained out of it. Asked "Do you like cats?", a bare "Sure" can mean anything from mild liking to polite indifference.
- 4Certainly or really, used in informal speech to stress a statement.
It sure is cold out here this morning, so grab a heavier coat.
You sure know how to make an entrance at a party.
UsageGoes before the verb in casual speech: it sure is cold. Formal writing prefers surely or certainly.
Note
In early modern verse, sure often meant without fail. Marlowe's Tamburlaine the Great promises a weapon that will "kill as sure as it swiftly flies." That older adverb often sits inside a comparison, as sure as, which gives it a proverbial ring.
Checked 2 Nov 2026 · 2 facts
- Christopher Marlowe wrote Tamburlaine the Great. gutenberg.org
- Tamburlaine describes a weapon that will kill as sure as it swiftly flies. gutenberg.org
- 5Placed first in a sentence to grant that something is true before raising a point that cuts against it.
Sure, the commute is long, but the rent is half what we paid downtown.
Sure, you could fix the leak yourself, but a plumber would have it done in ten minutes.
UsageUsually followed by but: Sure, the commute is long, but the rent is low.
Similargranted, admittedly
- 6Reliable and dependable; firm and not liable to fail.
Years of practice gave the climber a sure hold on even the smallest ledges.
A firm handshake was once thought a sure sign of honest character.
UsageCommon in a sure sign, a sure thing and a sure hold.
Similarreliable, dependable, firm, secure, steady
Oppositeunreliable, shaky, unsteady
Note
The Latin behind this sense is a little surprising: sēcūrus meant "carefree," built from sē- "apart" and cūra "care," the same cūra that gives English cure. What frees you from worry came to mean what will not fail you: a sure grip, a sure thing. The comparison is regular, surer and surest, as in Aldous Huxley's "infinitely surer methods" in Brave New World (1932).
Checked 31 Oct 2026 · 7 facts
- Sure derives ultimately from Latin sēcūrus, meaning carefree. en.wiktionary.org
- Sēcūrus combines sē-, meaning apart or without, and cūra, meaning care. en.wiktionary.org
- English cure also derives from Latin cūra. en.wiktionary.org
- Sure developed the meaning reliable or non-failing. en.wiktionary.org
- The comparative and superlative are surer and surest. en.wiktionary.org
- The exact phrase appears in Aldous Huxley's Brave New World; the fictional speaker is Mustapha Mond. fadedpage.com
- Brave New World was first published in 1932. fadedpage.com
Less common meanings
- 7Used as a polite, casual reply to thanks, much like you're welcome.
"Thank you so much for waiting for me." "Sure, no trouble at all."
"Thanks for covering my shift today." "Sure, you'd do the same for me."
Similaranytime
- 8Safe and secure; free from danger or harm.
Feare not: the Forreſt is not three leagues off, / If we recouer that, we are ſure enough.
c. 1590, William Shakespeare, “The Two Gentlemen of Verona”Note
In The Two Gentlemen of Verona, a fugitive says that once they reach the forest "we are sure enough." They mean safe, not confident. Of all the senses, this one stays closest to the Latin "carefree" behind the "reliable" meaning. It is obsolete, so read safe when you meet it in older texts, and use safe or secure in modern writing.
Checked 31 Oct 2026 · 4 facts
- Eglamour speaks the quoted words in The Two Gentlemen of Verona, referring to reaching the forest. folgerdigitaltexts.org
- The speaker is participating in an escape: Eglamour is accompanying the fleeing Silvia. gutenberg.org
- Sure means safe in this quotation. en.wiktionary.org
- The Latin ancestor has both carefree and safe meanings. en.wiktionary.org
- 9Promised in marriage; betrothed to another.
Note
To be sure to someone was once to be pledged to marry them. Thomas More writes that "the king was sure to Dame Elizabeth Lucy," and Richard Brome's The Northern Lass (1632) pairs it with "as fast as faith could bind you." Watch the construction: here sure to takes a person, unlike the to-infinitive of the "certain to happen" meaning. The sense is obsolete.
Checked 31 Oct 2026 · 6 facts
- To be sure to someone formerly meant to be pledged to marry them. thomasmorestudies.org
- Thomas More wrote the quoted words about Dame Elizabeth Lucy. thomasmorestudies.org
- Richard Brome wrote The Northern Lass, first published in 1632. dhi.ac.uk
- The Northern Lass pairs sure with the quoted phrase; Mistress Trainwell speaks the line. dhi.ac.uk
- The historical marriage construction takes a person after to. dhi.ac.uk
- The marriage sense is obsolete. en.wiktionary.org
Showing meanings only.
Practice
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Origin
Latin sēcūrus ("secure," literally "carefree"), made from sē- ("apart") and cūra ("care"), passed through Old French seür into Middle English as sure. Secure is a doublet, and sure gradually replaced the native Middle English siker ("certain, sure").
Checked 1 Nov 2026 · 5 facts
- Sure derives from Latin sēcūrus, meaning secure or literally carefree, through Old French seür and Middle English sure. en.wiktionary.org
- Latin sēcūrus combines sē- and cūra, expressing being apart from or without care. en.wiktionary.org
- Secure and sure are etymological doublets. en.wiktionary.org
- Sure gradually displaced the older English word siker; native here describes inherited English vocabulary, although its ultimate origin is Latin. uni-due.de
- Middle English siker meant certain or sure. en.wiktionary.org