*akwa-

"water," late 14c., from Latin aqua "water; the sea; rain," from PIE root *akwa- "water." The Latin word was used in late Middle English in combinations in old chemistry and alchemy in the sense of "decoction, solution" (as in aqua regia, a mix of concentrated acids, literally "royal water," so called for its power to dissolve gold and other "noble" metals; also see aqua fortis, aqua vitae). As the name of a light greenish-blue color, by 1936.

word-forming element meaning "water," from Latin aqua "water; the sea; rain," cognate with Proto-Germanic *akhwo (source of Old English ea "river," Gothic ahua "river, waters," Old Norse Ægir, name of the sea-god, Old English ieg "island"), from PIE root *akwa- "water."