Where
Old English hwǣr, of Germanic origin; related to Dutch waar and German wo .
wiktionary
From Middle English where, wher, whare, whar, hwere, hwer, hware, hwar, from Old English hwǣr(“where”, literally “at what place”), from Proto-Germanic *hwar(“where”), from Proto-Indo-European *kʷo-(interrogative pronoun). Cognate with Scots whaur(“where”), Saterland Frisian wier(“where”), West Frisian wêr(“where”), Dutch waar(“where”), German Low German waar(“where”), German wo(“where”), Danish and Norwegian Bokmål hvor(“where”), Norwegian Nynorsk kvar(“where”), Icelandic hvar(“where”); related to Old English hwā(“who”). More at who.
etymonline
where (adv.)
Old English hwær, hwar "at what place," from Proto-Germanic adverb *hwar (source also of Old Saxon hwar, Old Norse hvar, Old Frisian hwer, Middle Dutch waer, Old High German hwar, German wo, Gothic hvar "where"), equivalent to Latin cur, from PIE root *kwo-, stem of relative and interrogative pronouns. Where it's at attested from 1903.
It has figured in a great many prepositional and adverbial compounds through the years; in addition to the ones listed in this dictionary ( whereas, wherefore, whereabouts, etc.) English has or had whereagainst, wherefrom, wherehence, whereinsoever, whereinto, wheremid, whereout, whereover, whereso, wheresoever, wherethrough, whereto, whereunder, whereuntil.
