出典:Wiktionary
From Middle English which, hwic, wilche, hwilch, whilk, hwilc, from 古期英語 hwelċ (“which”), from Proto-Germanic *hwilīkaz (“what kind”, literally “like what”), derived from *hwaz, equivalent to who + like. Cognates include Scots whilk (“which”), West Frisian hokker (“which”), Dutch welk (“which”), Low German welk (“which”), German welcher (“which”), Danish hvilken (“which”), Swedish vilken (“which”), Norwegian hvilken (“which”), Icelandic hvílíkur (“which”).