if: [OE] The Old English version of if was gif, but its initial g was closer to modern English y in pronunciation than to g, and the conjunction gradually evolved through Middle English yif to if. It is not known where it ultimately came from; it is evidently connected with Old High German iba ‘condition’ and Old Norse ef ‘doubt’, but whether it started life as a noun like these or was from the beginning a conjunction is not clear. Its surviving Germanic relatives are German ob ‘whether’ and Dutch of ‘if’. [if etymology, if origin, 英语词源]