duck n.1

waterfowl, natatorial bird of the family Anatidae, Old English duce (found only in genitive ducan) "a duck," literally "a ducker," presumed to be from Old English *ducan "to duck, dive" (see duck (v.)). Replaced Old English ened as the name for the bird, this being from PIE *aneti-, the root of the "duck" noun in most Indo-European languages.

In the domestic state the females greatly exceed in number, hence duck serves at once as the name of the female and of the race, drake being a specific term of sex. [OED]

As a term of endearment, attested from 1580s (see ducky). duck-walk, a squatting waddle done by a person, in imitation of a duck, is by 1915; duck soup, slang for "anything easily done," is by 1899. Duck's ass haircut is from 1951. Ducks-and-drakes, skipping flat stones on water, is from 1580s; the figurative sense of "throwing something away recklessly" is c. 1600.

"strong, untwilled linen (later cotton) fabric," used for sails and sailors' clothing, 1630s, from Dutch doeck "linen cloth" (Middle Dutch doec), from Proto-Germanic *dōkaz, a word of uncertain etymology (source also of German Tuch "piece of cloth," Danish dug, Old Frisian dok, Old High German tuoh).

c. 1300, "to plunge into" (transitive); mid-14c., "to suddenly go under water and immediately withdraw" (intransitive); from a presumed Old English *ducan "to duck," found only in derivative duce (n.) "duck" (but there are cognate words in other Germanic languages, such as Old High German tuhhan "to dip," German tauchen "to dive," Old Frisian duka, Middle Dutch duken "to dip, dive," Dutch duiken), from Proto-Germanic *dukjanan.

The sense of "to lower or bend down suddenly, stoop quickly," as in dodging, is recorded by 1520s. Related: Ducked; ducking. The noun is attested from 1550s in the sense of "a quick stoop;" meaning "a plunge, a dip" is from 1843.