n.
Function: conjunction
Etymology: Middle English, from Old English hwanne, hwenne, from hwanne, hwenne, adverb
Date: before 12th century
1 a : at or during the time that : WHILE <went fishing when he was a boy> b : just at the moment that <stop writing when the bell rings> c : at any or every time that < when he listens to music, he falls asleep>
2 : in the event that : IF <a contestant is disqualified when he disobeys the rules>
3 a : considering that <why use water at all when you can drown in it ― Stuart Chase> b : in spite of the fact that : ALTHOUGH <quit politics when I might have had a great career in it>
4 : the time or occasion at or in which <tomorrow is when we must decide> <humor is when you laugh ― Earl Rovit>