Hygiene
late 16th century: via French from modern Latin hygieina, from Greek hugieinē (tekhnē) ‘(art) of health’, from hugiēs ‘healthy’.
wiktionary
From French hygiène, from Ancient Greek ὑγιεινή ( τέχνη)(hugieinḗ (tékhnē), literally “art of health”), from ὑγιεινός(hugieinós, “of health, good for the health, wholesome, sound, healthy”), from ὑγιής(hugiḗs, “healthy, sound”).
etymonline
hygiene (n.)
1670s, from French hygiène, ultimately from Greek hygieine techne "the healthful art," from hygies "healthy, sound, hearty," literally "living well" (personified as the goddess Hygieia), from PIE *eyu-gwie-es- "having a vigorous life," from root *aiw-, *ayu- "vital force, life, long life, eternity; in the prime of life, young" (source of Latin aevus, English ever). The Greek adjective was used by Aristotle as a noun meaning "health." The difficult spelling in English is a relic of the struggle to render the Greek vowels into French.
