hygiene (n.) Look up hygiene at Dictionary.com
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; see eon). 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.