The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
aiw-
DEFINITION:
Also ayu-. Vital force, life, long life, eternity; also “endowed with the acme of vital force, young.” Oldest forms *2eiw-, *2eyu-, colored to *2aiw-, *2ayu-. Derivatives include no1, ever, medieval, age, and eon. 1a.no1, from Old English , ever; b.aught1, from Old English wiht,uht, anything, “ever a creature”; c.ever; every, never, from Old English fre (second element obscure), ever; d.aye2; nay, from Old Norse ei, ever. a, c, and d all from extended Germanic form *aiwi;b from Germanic *aiwi + *wihti, “ever a thing, anything” (*wihti-, thing; see wekti-). 2a. Suffixed form *aiw-o-.coeval, longevity, medieval, primeval, from Latin aevum, age, eternity; b. further suffixed form *aiwo-t(ti)-.age; coetaneous, from Latin aets (stem aetti-), age; c. further suffixed form *aiwo-t-erno-.eternal, eterne, eternity; sempiternal, from Latin aeternus, eternal. 3. Suffixed form *aiw-en-.eon, from Greek ain, age, vital force. 4. Zero-grade form *yu- (earlier *yu-) in compound *yu-gwi-es-, “having a vigorous life” (*gwi-es-, life; see gwei-). hygiene, from Greek hugis, healthy. 5. O-grade form *oyu- (earlier *oyu-). a.utopia, from Greek ou, not, variant of ouk, probably from a pre-Greek phrase *(ne) oyu (kwid), “(not on your) life” (ne, not, and *kwid, indefinite pronoun used as emphasizing particle; see ne and kwo-); b.Ayurveda, from Sanskrit yu, life, health, from suffixed form *oyu-s-. (Pokorny ai- 17.) See also derivative yeu-.
2eiw-, *
, ever; b. aught1, from Old English 
fre (second element obscure), ever; d. aye2; nay, from Old Norse ei, ever. a, c, and d all from extended Germanic form *aiwi; b from Germanic *aiwi + *wihti, “ever a thing, anything” (*wihti-, thing; see wekti-). 2a. Suffixed form *aiw-o-. coeval, longevity, medieval, primeval, from Latin aevum, age, eternity; b. further suffixed form *aiwo-t
n, age, vital force. 4. Zero-grade form *yu- (earlier *
s, healthy. 5. O-grade form *oyu- (earlier *
, life, health, from suffixed form *oyu-s-. (Pokorny ai
- 17.) See also derivative yeu-. 
