drowsyyoudaoicibaDictYouDict[drowsy 词源字典]
drowsy: [15] The etymological notion underlying drowsy seems to be of heaviness, with eyelids falling and the head nodding over the chest. The word probably comes from a Germanic base *drūs-, which also produced drūsian, an Old English verb meaning ‘be slow and sleepy’ which did not survive into the Middle English period (modern English drowse [16] is a back-formation from drowsy). A variant of this base is the possible source of English dreary and drizzle.
=> dream, drizzle[drowsy etymology, drowsy origin, 英语词源]
drowsy (adj.)youdaoicibaDictYouDict
1520s, probably ultimately from Old English drusan, drusian "sink," also "become languid, slow, or inactive" (related to dreosan "to fall"), from Proto-Germanic *drus- (see dreary). But there is no record of it in Middle English. Related: Drowsily; drowsiness.