Etymology: Middle English, from Old English hwām, dative of hwā who
Date: before 12th century
objective case of who — used as an interrogative or relative; used as object of a verb or a preceding preposition <to know for whom the bell tolls — John Donne> or less frequently as the object of a following preposition <the man whom you wrote to> though now often considered stilted especially as an interrogative and especially in oral use — occasionally used as predicate nominative with a copulative verb or as subject of a verb especially in the vicinity of a preposition or a verb of which it might mistakenly be considered the object <whom say ye that I am — Matthew 16:15 (Authorized Version)> <people…whom you never thought would sympathize — Shea Murphy> Usage: Observers of the language have been predicting the demise of whom from about 1870 down to the present day <one of the pronoun cases is visibly disappearing—the objective case whom — R. G. White (1870)> <whom is dying out in England, where “Whom did you see?” sounds affected — Anthony Burgess (1980)>. Our evidence shows that no one—English or not—should expect whom to disappear momentarily; it shows every indication of persisting quite a while yet. Actual usage of who and whom—accurately described at the entries in this dictionary—does not appear to be markedly different from the usage of Shakespeare's time. But the 18th century grammarians, propounding rules and analogies, rejecting other rules and analogies, and usually justifying both with appeals to Latin or Greek, have intervened between us and Shakespeare. It seems clear that the grammarians' rules have had little effect on the traditional uses. One thing they have accomplished is to encourage hypercorrect uses of whom <whom shall I say is calling?>. Another is that they have made some people unsure of themselves <said he was asked to step down, although it is not known exactly who or whom asked him — Redding (Connecticut) Pilot>.
New Collegiate Dictionary. 2001.