plunge (v.)youdaoicibaDictYouDict[plunge 词源字典]
late 14c., "to put or thrust violently into," also intransitive, from Old French plongier "plunge, sink into; plunge into, dive in" (mid-12c., Modern French plonger), from Vulgar Latin *plumbicare "to heave the lead," from Latin plumbum "lead" (see plumb (n.)). Original notion perhaps is of a sounding lead or a fishing net weighted with lead. Related: Plunged; plunging. Plunging neckline attested from 1949.[plunge etymology, plunge origin, 英语词源]
troglodyte (n.)youdaoicibaDictYouDict
"cave-dweller," 1550s, from Middle French troglodyte and directly from Latin troglodytae (plural), from Greek troglodytes "cave-dweller, cave-man" (in reference to tribes identified as living in various places by ancient writers; by Herodotus on the African coast of the Red Sea), literally "one who creeps into holes," from trogle "hole, mouse-hole" (from trogein "to gnaw, nibble, munch;" see trout) + dyein "go in, dive in." Related: Troglodytic.