when

Origin

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 you want me to stop) as "say [the word] when".