"easy," 1915, Anglo-Indian slang, from Hindi khush "pleasant, healthy, happy" + -y (2). Wright's "English Dialect Dictionary" (1898) has cush "a soft, useless person," identified as Scottish and Northumberland and explained as "A common term of reproach, used of one who allows others to beat him, either in self-defence or at work," hence cushie "soft, flabby."
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.
late 14c., "guardian, custodian," from Old French tuteor "guardian, private teacher" (13c., Modern French tuteur), from Latin tutorem (nominative tutor) "guardian, watcher," from tutus, variant past participle of tueri "watch over, look at," a word of uncertain origin. De Vaan suggests the sense evolution is from "to protect," and suggests connection with Sanskrit tavas- "strong, powerful," Greek sōs "safe, safe and sound, healthy," from a root meaning "to be strong." Specific sense of "senior boy appointed to help a junior in his studies" is recorded from 1680s.
salutation in greeting, c. 1200, from Old Norse heill "health, prosperity, good luck," or a similar Scandinavian source, and in part from Old English shortening of wæs hæil "be healthy" (see health; and compare wassail).
The interj. hail is thus an abbreviated sentence expressing a wish, 'be whole,' i. e., be in good health, and equiv. to L. salve, plural salvete, or ave, plural avete .... [Century Dictionary]
1719, alteration of salva (1590s) "simultaneous discharge of guns," from Italian salva "salute, volley" (French salve, 16c., is from Italian), from Latin salve "hail!," literally "be in good health!," the usual Roman greeting, regarded as imperative of salvere "to be in good health," but properly vocative of salvus "healthy" (from PIE root *sol- "whole, well-kept"). The notion is of important visitors greeted with a volley of gunfire into the air; applied afterward to any concentrated fire from guns.