drabyoudaoicibaDictYouDict[drab 词源字典]
drab: [16] Drab is a variant of the now obsolete form drap, which was borrowed from Old French drap ‘cloth’ (source also of English drape, draper, and trappings). It was originally a noun meaning ‘cloth’ in English too, but the beginnings of its transition to the modern English adjective meaning ‘faded and dull’ can be seen in the 17th century.

The word came to be used particularly for natural undyed cloth, of a dull yellowish-brown colour, and hence for the colour itself (an application best preserved in the olive-drab colour of American service uniforms). The figurative development to ‘dull and faded’ is a comparatively recent one, first recorded a little over a hundred years ago.
=> drape, trappings[drab etymology, drab origin, 英语词源]
drab (n.)youdaoicibaDictYouDict
1680s, "color of natural, undyed cloth," from Middle French drap "cloth, piece of cloth" (see drape (v.)). Figurative sense is c. 1880. Apparently not related to earlier word drab, meaning "a dirty, untidy woman" (1510s), "a prostitute" (1520s), which might be related to Irish drabog, Gaelic drabag "dirty woman," or perhaps it is connected with Low German drabbe "dirt;" compare drabble (Middle English drabelen) "to soil (something); trail in the mud or on the ground" (c. 1400). Ultimately perhaps from PIE *dher- (1) "to make muddy." Meaning "small, petty debt" (the sense in dribs and drabs) is 1828, of uncertain connection to the other senses.