The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
kwo-
DEFINITION:
Also kwi-. Stem of relative and interrogative pronouns. Derivatives include who, whether, either, quorum, quip, and quality. 1a.who, whose, whom, from Old English hw,hwæs,hwm, who, whose, whom, from Germanic personal pronouns *hwas,*hwasa,*hwam;b.what, from Old English hwæt, what, from Germanic pronoun *hwat;c.why, from Old English hw, why, from Germanic adverb *hw;d.which, from Old English hwilc,hwelc, which, from Germanic relative pronoun *hwa-lk- (*lk-, body, form; see lk-); e.how, from Old English h, how, from Germanic adverb *hw;f. (i)when, from Old English hwenne,hwanne, when; (ii)whence, from Old English hwanon, whence. Both (i) and (ii) from Germanic adverb *hwan-;g.whither, from Old English hwider, whither, from Germanic adverb *hwithr;h.where, from Old English hwr, where, from Germanic adverb *hwar-.a–h all from Germanic *hwa-,*hwi-.2a.whether; neither, from Old English hwæther,hwether, which of two, whether; b.either, from Old English ghwæther,ther, either, from Germanic phrase *aiwo gihwatharaz, “ever each of two” (*aiwo,*aiwi, ever, and *gi- from *ga-, collective prefix; see aiw- and kom). Both a and b from Germanic *hwatharaz.3.qua, quibble, quorum, from Latin qu, who. 4.hidalgo, quiddity, quidnunc, quip; kickshaw, from Latin quid, what, something. 5.quasi, from Latin quasi, as if (< quam + s, if; see swo-), from quam, as, than, how. 6.quodlibet, from Latin quod, what. 7. Suffixed form *kwo-ti.a.quote, quotidian, quotient; aliquot, from Latin quot, how many; b. further suffixed form *kwo-ty-o-.posology, from Greek posos, how much. 8.quondam, from Latin quom, when. 9.cooncan, from Latin quem, whom. 10.quantity, from Latin quantus, how great. 11.quality; kickshaw, from Latin qulis, of what kind. 12.cue2, from Latin quand, when (from *kwm + -d, to, til; see de-). 13.neuter, from Latin uter, either of two, ultimately from *kwo-tero- (becoming -cuter in such compounds as necuter, neither, from which uter was abstracted out by false segmentation). 14.ubiquity, from Latin ubi, where, ultimately from locative case *kwo-bhi (becoming -cubi in such compounds as alicubi, somewhere, from which ubi was abstracted out by false segmentation, perhaps under the influence of ibi, there). 15.cheese3, from Old Persian *ci-ciy, something ( < *kwid-kwid). (Pokorny ko- 644.)
, hwæs, hw
m, who, whose, whom, from Germanic personal pronouns *hwas, *hwasa, *hwam; b. what, from Old English hwæt, what, from Germanic pronoun *hwat; c. why, from Old English hw
, why, from Germanic adverb *hw
; d. which, from Old English hwilc, hwelc, which, from Germanic relative pronoun *hwa-l
, how, from Germanic adverb *hw
; f. (i) when, from Old English hwenne, hwanne, when; (ii) whence, from Old English hwanon, whence. Both (i) and (ii) from Germanic adverb *hwan-; g. whither, from Old English hwider, whither, from Germanic adverb *hwithr
; h. where, from Old English hw
-ciy, something ( < *kwid-kwid). (Pokorny k
o- 644.) 
