When  —interrog. Adv. 1 at what time? 2 on what occasion? 3 how soon? —rel. Adv. (prec. By time etc.) At or on which (there are times when i could cry). —conj. 1 at the or any time that; as soon as (come when you like; come when ready). 2 although (why stand when you could sit?). 3 after which; and then; but just then (was nearly asleep when the bell rang). —pron. What time?; which time (till when can you stay?; since when it has improved). —n. Time, occasion (fixed the where and when). [old english]