duck (n.1) Look up duck at Dictionary.com
waterfowl, 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. duck-walk is 1930s; duck soup "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.
duck (n.2) Look up duck at Dictionary.com
"strong, untwilled linen (later cotton) fabric," used for sails and sailors' clothing, 1630s, from Dutch doeck "linen cloth" (Middle Dutch doec), related to German Tuch "piece of cloth," Danish dug, Old Frisian dok, Old High German tuoh, all of unknown origin.
duck (v.) Look up duck at Dictionary.com
"to plunge into" (transitive), c.1300; to suddenly go under water (intransitive), mid-14c., from 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 *dukjan.

Sense of "bend, stoop quickly" is first recorded in English 1520s. Related: Ducked; ducking. The noun is attested from 1550s in the sense of "quick stoop;" meaning "a plunge, dip" is from 1843.