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]
"frozen rain, pellets of ice falling in showers," Old English hægl, hagol (Mercian hegel) "hail, hailstorm," also the name of the rune for H, from Proto-Germanic *haglaz (source also of Old Frisian heil, Old Saxon, Old High German hagal, Old Norse hagl, German Hagel "hail"), probably from PIE *kaghlo- "pebble" (source also of Greek kakhlex "round pebble").
"to greet or address with 'hail!,'" also "to drink toasts," c. 1200, heilen; to call to from a distance," 1560s (in this sense originally nautical), from hail (interj.). Related: Hailed; hailing. Bartlett ["Dictionary of Americanisms," 1848] identifies to hail from (1841) as "a phrase probably originating with seamen or boatmen." Hail fellow well met is from 1580s as a descriptive adjective, from a familiar greeting; hail fellow (adj.) "overly familiar" is from 1570s. Hail Mary (c. 1300) is the angelic salutation (Latin ave Maria) in Luke i.58, used as a devotional recitation. As a desperation play in U.S. football, attested by 1940. "Hail, Columbia," the popular patriotic song, also was a euphemism for "hell" in American English slang from c. 1850-1910.
Old English hagalian "to fall as hail," from root of hail (n.). Related: Hailed; hailing. Figurative use from mid-15c.