adverb

1. 1. at what time? when did they leave? he asked when he should go
   2. on what occasion or under what circumstances? when do you double the final consonant?
   3. at what point? when shall I stop pouring?
2. at an earlier time and under different, often less favorable, circumstances I knew him when

Etymology: ME whenne < OE hwænne, akin to Ger wann, when, wenn, if, akin to hwa, who: see what

conjunction

1. 1. at what time or point they told us when to eat
   2. at the time that when we were at college
2. at which a time when people must speak out
3. as soon as the runners started when the gun went off
4. at whatever time; whenever she smiles when you praise her
5. although; while on the contrary to complain when there's no reason to do so
6. if; considering the fact that how can he help when they won't let him?

pronoun

1. what time until when will you stay?
2. which time we came a week ago, since when we've been very busy

noun