also dishwater, "water in which dishes have been washed," late 15c., from dish (n.) + water (n.1). Used figuratively of weak broth, coffee, etc. from 1719. Earlier in Middle English was dischwaschyngs (c. 1300).
Old English disc "plate, bowl, platter," from Latin discus "dish, platter, quoit," in Medieval Latin "a table, dais, desk, pulpit," from Greek diskos "disk, platter" (see disk (n.)).
A common West Germanic borrowing; Old High German took the word as tisc "plate," but German Tisch now means "table," in common with some other later Romanic forms of Latin discus (such as Italian desco, French dais); compare desk (n.), dais.
Meaning "particular variety of food served in a dish" is first recorded mid-15c. Meaning "what one likes, what is suited to one's taste" is by 1918; that of "attractive woman" is 1920s. Meaning "concave reflector or antenna" attested from 1948.
Originally applied to very shallow or flat vessels, as plates and platters, the term now usually includes any large open vessel, more or less deep, and with or without a cover, used to contain food or table-drink such as tea, coffee, or chocolate. The use of the term to include drinking-vessels, as bowls and cups, is less common, and seems to be obsolescent, except as such vessels are included in the collective plural dishes. [Century Dictionary, 1897]
Old English wæter, from Proto-Germanic *watr- (source also of Old Saxon watar, Old Frisian wetir, Dutch water, Old High German wazzar, German Wasser, Old Norse vatn, Gothic wato "water"), from PIE *wod-or, suffixed form of root *wed- (1) "water; wet."
To keep (one's) head above water in the figurative sense is recorded from 1742. Water cooler is recorded from 1846; water polo from 1884; water torture from 1928. Linguists believe PIE had two root words for water: *ap- and *wed-. The first (preserved in Sanskrit apah as well as Punjab and julep) was "animate," referring to water as a living force; the latter referred to it as an inanimate substance. The same probably was true of fire (n.).