when

Pluralwhens

1. 1
   at the time thatconjunction

   At, during, or as soon as the time that; at any time that; or if.

   Call me when you get home.

   The alarm sounds when smoke reaches the sensor.

   UsageFor the future, use the present after it: call me when you get home (not incorrect: when you will get home).

   Similarwhenever, once, if

   Note

   The clause can mark a single moment or state a standing rule, and the difference changes the meaning. 'Put your pencil down when the timer goes off' marks one instant. 'Pavlov's dogs salivate when they hear a bell' means every time, close to 'whenever', and in a game rule it slides toward 'if'. It can also mark time that overlaps rather than triggers, meaning 'while' or 'during the time that'. Source

   Checked 30 Oct 2026 · 1 fact

   • Pavlov's dogs were conditioned to salivate at the sound of a bell. psychology.uga.edu
2. 2
   time asked aboutadverbinterrogative

   At what time or on what occasion, in direct or indirect questions; online, also placed after a noun to ask when something awaited will happen ('update when?').

   When did you last see her?

   Do you happen to know when the last bus leaves tonight?

   UsageAsk how long for a length of time. Indirect questions keep statement order: I know when it leaves (not incorrect: when does it leave).

   Note

   An indirect question can even fill the subject slot of a sentence, as in 'when they arrived is unknown', where the whole clause is what the verb describes. Source

   Checked 3 Nov 2026 · 1 fact

   • An indirect question can function as the subject of a sentence, as in the example given. human.libretexts.org
3. 3
   adverbrelative

   At, on, or during which; the time at which, used after a noun for a time or on its own.

   I remember the summer when we met.

   There are days when I wish I had stayed in my hometown.

   UsageYou can often leave out when after a time noun: the day (when) we met.

   Note

   The noun need not name a single date, since 'not a week goes by when I don't mourn' works just as well. A novel of 1897 uses both 'a certain afternoon when' and 'at a time when'. Source

   Checked 2 Nov 2026 · 2 facts

   • The novel contains the exact phrase 'a certain afternoon when'. gutenberg.org
   • The same novel contains the exact phrase 'at a time when'. gutenberg.org
4. 4
   conjunction

   And at that time; introducing a new event that continues a narrative or follows a stated time.

   She had just sat down when the phone rang.

   He worked there until 2010, when the factory closed.

   UsageOften after a past continuous or had just: we were walking home when it began to rain.

   Note

   Narrative 'when' moves the story forward. The clause it introduces is the new event, not the backdrop, much like 'and then'. It usually follows a comma, and a 1929 account even puts it after a semicolon ('soon had the job done; when we were admitted to the kitchen'). It can also pick up a named time, as in 'till Friday, when I leave for Senegal'. Source

   Checked 30 Oct 2026 · 3 facts

   • The cited account was published in 1929. catalog.hathitrust.org
   • The account places 'when we were admitted to the kitchen' after a semicolon. en.wiktionary.org
   • The source reads 'we buckled to and soon had the job done'. Delete the initial 'we' from the note's excerpt to make it an exact quotation. en.wiktionary.org
5. 5
   pronouninterrogative

   What time or which time, used after a preposition.

   Until when is the offer open?

   The sign says the road is closed, but it doesn't say until when.

   UsageSince when often sounds like a challenge, not a real question: since when do I need your permission?

   Note

   It counts as a pronoun here because it is the object of a preposition: since when, till when. 'Since when do I need your permission?' works as a challenge rather than a real question. Older writers used the pair neutrally: The Tempest has 'till when, be cheerful', and a nineteenth-century medical treatise writes 'since when, we have altogether abandoned their use', meaning 'since which time'. Source

   Checked 30 Oct 2026 · 3 facts

   • The Tempest contains 'till when, be cheerful', used neutrally. folger.edu
   • William Potts Dewees's A Treatise on the Diseases of Females was first published in 1826; 1833 is the fourth edition. collections.nlm.nih.gov
   • The medical treatise contains 'since when, we have altogether abandoned their use', meaning 'since which time'. en.wiktionary.org
6. 6
   conjunction

   Whereas or although, introducing a fact that contrasts with what has just been said, often what ought to be the case instead.

   She spends hours online when she should be sleeping.

   They complain about the cost when they never paid a penny.

   UsageOften with should: you're playing when you should be working.

   Similaralthough, whereas

   Note

   Time language serves here as a reproach. The construction is old: a play doubtfully credited to Beaumont and Fletcher asks how to deserve the age's smiles 'when I am only rich in misery'. Close kin to the 'given that' meaning, it argues against rather than for. Source

   Checked 3 Nov 2026 · 3 facts

   • The construction occurs in an old play: The Knight of the Burning Pestle, first published in 1613. gutenberg.ca
   • The play has been credited jointly to Beaumont and Fletcher, although that attribution has been disputed; modern editions generally credit Beaumont alone. en.wikipedia.org
   • Jasper asks how to deserve the age's smiles and says the quoted words in The Knight of the Burning Pestle, scene 2.3. emothe.uv.es
7. 7
   conjunction

   Since, given that, or considering that, presenting a reason as a circumstance.

   Why buy a car when the bus stops outside your door?

   Why should I pay for a taxi when the station is only a short walk away?

   UsageOften in a question that argues a point: why walk when you can ride?

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