1550s, "a tuft or plume of feathers," especially as worn in a hat or helmet, from French pennache "tuft of feathers," from Italian pennaccio, from Late Latin pinnaculum "small wing, gable, peak" (see pinnacle). Figurative sense of "display, swagger" is recorded from 1898 (in translation of "Cyrano de Bergerac"), from French.
female pudendum, 1650s, of unknown origin. A general term of abuse since 1920s.
The T-word occupies a special niche in literary history, however, thanks to a horrible mistake by Robert Browning, who included it in 'Pippa Passes' (1841) without knowing its true meaning. 'The[n] owls and bats,/Cowls and twats,/Monks and nuns,/In a cloister's moods.' Poor Robert! He had been misled into thinking the word meant 'hat' by its appearance in 'Vanity of Vanities,' a poem of 1660, containing the treacherous lines: 'They'd talk't of his having a Cardinalls Hat,/They'd send him as soon an Old Nuns Twat.' (There is a lesson here about not using words unless one is very sure of their meaning.) [Hugh Rawson, "Wicked Words," 1989]
"amorous or designing widow," 1907, from the English title of Franz Lehar's operetta "Die Lustige Witwe" (1905). "The Lusty Widow" would have been more etymological (see lust (n.)), but would have given the wrong impression in English. Meaning "a type of wide-brimmed hat" (popularized in the play) is attested from 1908.
also chako, cylindrical soldier's hat with plume, 1815, from Hungarian csákó, short for csákós süveg "peaked cap," from adjectival form of csáko "peak, projecting point of a cow's horn," which some European etymologists derive from German zacken "point, spike," but which Hungarian sources regard as of unknown origin.
species of tall herbs native to Europe and western Asia, 1660s, a Modern Latin translation of German fingerhut, the German name of the plant, a transferred use of the German word for "thimble," literally "finger-hat," the plant so called for the bell-shape of the flowers. Compare the English name, foxglove. The Latin name was given by Fuchs (1542). The medicine (originally extracted from the plant) is so called from 1799.
"put or take off" an article of clothing, especially a hat or cap, late 14c., doffen, a contraction of do off, preserving the original sense of do as "put." At the time of Johnson's Dictionary  the word was "obsolete, and rarely used except by rustics," and also in literature as a conscious archaism, but it was saved from extinction (along with don (v.)) by Sir Walter Scott. However, dout and dup did not survive. Related: Doffed; doffing.
"pattern consisting of dots of uniform size and arrangement," especially on fabric, 1851 (polka-spot and polka-dotted are used in 1849), when they were in fashion, from polka (n.) + dot (n.). Named for the dance, for no reason except its popularity, which led to many contemporary products and fashions taking the name (polka hat, polka-jacket, etc.). They had a revival in fashion c. 1873. Related: Polka-dots.
type of edible European mollusk, early 14c., from Old French coquille (13c.) "scallop, scallop shell; mother of pearl; a kind of hat," altered (by influence of coque "shell") from Vulgar Latin *conchilia, from Latin conchylium "mussel, shellfish," from Greek konkhylion "little shellfish," from konkhē "mussel, conch." Phrase cockles of the heart "inmost recesses of one's spirit" (1660s) is perhaps from similar shape, or from Latin corculum, diminutive of cor "heart." Cockle-shell attested from early 15c.