when

Meanings

1. 1
   adv

   At what time? At which time? Upon which occasion or circumstance? Used to introduce direct or indirect questions about time.

   When will they arrive?

2. 2
   adv

   At an earlier time and under different, usually less favorable, circumstances.

   He's mister high and mighty now, but I remember him when.

3. 3
   adv

   At which, on which, during which: often omitted or replaced with that.

   That was the day when the Twin Towers fell.

4. 4
   adv

   The time at, on or during which.

   I recall when they were called the Greys.

5. 5
   adv

   A circumstance or situation in which.

   Love is when you can't get enough of someone.

6. 6
   conj

   At (or as soon as) that time that; at the (or any and every) time that; if.

   Pavlov's dogs salivate when [i.e. at any and every time that] they hear a bell.

7. 7
   conj

   During the time that; at the time of the action of the following clause or participle phrase.

   They dream when [i.e. during the time that] they sleep.

8. 8
   conj

   At what time; at which time.

   I am here till Friday, when [i.e. at which time] I leave for Senegal.

Etymology

From Middle English when(ne), whan(ne), from Old English hwonne, from Proto-West Germanic *hwannē, from Proto-West Germanic *hwan, from Proto-Germanic *hwan (“at what time, when”), from Proto-Indo-European *kʷís (interrogative base). Cognate with Scots whan (“when”), Dutch wanneer (“when”), wan (“when”) and wen (“when, if”), Low German wannehr (“when”), wann (“when”) and wenn (“if, when”), German wann (“when”) and wenn (“when, if”), Gothic 𐍈𐌰𐌽 (ƕan, “when, how”), Latin quandō (“when”). More at who. Interjection sense: a playful misunderstanding of "say when" (i.e. say something / speak up when…