It forms all or part of: apotropaic; atropine; Atropos; contrive; entropy; heliotrope; isotropic; psychotropic; retrieve; trope; -trope; trophy; tropic; tropical; tropism; troposphere; troubadour; zoetrope.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit trapate "is ashamed, confused," properly "turns away in shame;" Greek trepein "to turn," tropos "a turn, direction, course," trope "a turning;" Latin trepit "he turns."
"a form in which an element having the property of allotropy may exist," 1847, a back-formation from allotropy "variation of physical properties without change of substance," from Greek allotropos "in another manner;" see allo- "different" + -trope "way, manner." Diamond is an allotrope of carbon. Related: Allotropic.
1540s, "body of soldiers," 1540s, from French troupe, from Old French trope "band of people, company, troop, crowd" (13c.), a word of uncertain origin, perhaps from Frankish *throp "assembly, gathering of people" or another Germanic source, perhaps related to Old English ðorp, Old Norse thorp "village" (see thorp). OED derives the French word from Latin troppus "flock," which is of unknown origin but also might be from the proposed Germanic source. Of groups of animals from 1580s. Specifically as "a subdivision of a cavalry force" from 1580s; of Boy Scouts from 1908. Troops "armed forces" is from 1590s.
in rhetoric, a trope or figure of speech in which the name of one thing is substituted for that of another that is suggested by or closely associated with it (such as the bottle for "alcoholic drink," the Kremlin for "the Russian government"); 1560s, from French métonymie (16c.) and directly from Late Latin metonymia, from Greek metōnymia, literally "change of name," related to metonomazein "to call by a new name; to take a new name," from meta "change" (see meta-) + onyma, dialectal form of onoma "name" (from PIE root *no-men- "name"). It often serves to call up associations not suggested by the literal name. Related: Metonymic; metonymical; metonymically.