whoever (pron.)

Old English hwa "who," sometimes "what; anyone, someone; each; whosoever," from Proto-Germanic *hwas (source also of Old Saxon hwe, Danish hvo, Swedish vem, Old Frisian hwa, Dutch wie, Old High German hwer, German wer, Gothic hvo (fem.) "who"), from PIE root *kwo-, stem of relative and interrogative pronouns.

Old English æfre "ever, at any time, always;" of uncertain origin, no cognates in any other Germanic language; perhaps a contraction of a in feore, literally "ever in life" (the expression a to fore is common in Old English writings). First element is almost certainly related to Old English a "always, ever," from Proto-Germanic *aiwi-, extended form of PIE root *aiw- "vital force, life; long life, eternity." Liberman suggests second element is comparative adjectival suffix -re.

Sometimes contracted to e'er in dialect and poetry. Ever began to be used in late Old English as a way to generalize or intensify when, what, where, etc. The sense evolution was from "at any time at all, in any way" to "at any particular time; at some time or another; under any circumstances." Ever so "to whatever extent" is recorded by 1680s. Expression did you ever? (implying "see/do/hear of such a thing") attested by 1840.

also *kwi-, Proto-Indo-European root, stem of relative and interrogative pronouns.

It forms all or part of: cheese (n.2) "a big thing;" cue (n.1) "stage direction;" either; hidalgo; how; kickshaw; neither; neuter; qua; quality; quandary; quantity; quasar; quasi; quasi-; query; quib; quibble; quiddity; quidnunc; quip; quodlibet; quondam; quorum; quote; quotidian; quotient; ubi; ubiquity; what; when; whence; where; whether; which; whither; who; whoever; whom; whose; why.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit kah "who, which;" Avestan ko, Hittite kuish "who;" Latin quis/quid "in what respect, to what extent; how, why," qua "where, which way," qui/quae/quod "who, which;" Lithuanian kas "who;" Old Church Slavonic kuto, Russian kto "who;" Old Irish ce, Welsh pwy "who;" Old English hwa, hwæt, hwær, etc.