Online Etymology Dictionary

trope: 1533, from L. tropus "a figure of speech," from Gk. tropos "turn, direction, turn or figure of speech," related to trope "a turning" and trepein "to turn," from PIE base trep- "to turn" (cf. Skt. trapate "is ashamed, confused," prop. "turns away in shame;" L. trepit "he turns"). Technically, in rhetoric, a figure of speech which consists in the use of a word or phrase in a sense other than that which is proper to it.
-trope: comb. form meaning "that which turns," from Gk. tropos (see trope).
entropy: 1868, from Ger. Entropie "measure of the disorder of a system," coined 1865 (on analogy of Ger. Energie) by physicist Rudolph Clausius (1822-1888) from Gk. entropia "a turning toward," from en- "in" + trope "a turning" (see trope).
zoetrope: 1867, lit. "wheel of life," from Gk. zoe "life" (see zoo) + trope "turn" (see trope).
trophy: 1513, "a spoil or prize of war," from M.Fr. trophée (15c.) from L. trophæum "a sign of victory, monument," originally tropæum, from Gk. tropaion "monument of an enemy's defeat," from neut. of adj. tropaios "of defeat," from trope "a rout," originally "a turning" (of the enemy); see trope. Figurative extension to any token or memorial of victory is first recorded 1569. Trophy wife attested "by 1984," according to "Dictionary of American Slang."
tropic: c.1391, "either of the two circles in the celestial sphere which describe the northernmost and southernmost points of the ecliptic," from L.L. tropicus "of or pertaining to the solstice" (as a noun, "one of the tropics"), from L. tropicus "pertaining to a turn," from Gk. tropikos "of or pertaining to a turn or change, or to the solstice" (as a noun, "the solstice"), from trope "a turning" (see trope). The notion is of the point at which the sun "turns back" after reaching its northernmost or southernmost point in the sky. Extended 1527 to the corresponding latitudes on the earth's surface (23 degrees 28 minutes north and south); meaning "region between these parallels" is from 1837. Tropical "hot and lush like the climate of the tropics" is first attested 1834.
tropism: 1899, "tendency of an animal or plant to turn or move in response to a stimulus," abstracted from geotropism, ult. from Gk. tropos (see trope).
Atropos: one of the Fates (the one who holds the shears and determines the manner of a person's death and cuts the thread), from Gk., "inflexible," lit. "not to be turned away," from a- "not" + stem of trepein "to turn" (see trope). Related form Atropa was the Gk. name for deadly nightshade.
allotrope: from allotropy "variation of physical properties without change of substance," from allo-, comb. form of Gk. allos "other, different" + tropos "manner" (see trope).
psychotropic: 1956, from psycho- + Gk. -tropos "turning," from trepein (see trope). Hence, what "turns" the mind.
troposphere: 1914, from Fr. troposphère, lit. "sphere of change," coined by Fr. meteorologist Philippe Teisserenc de Bort (1855-1913) from Gk. tropos "a turn, change" (see trope) + sphaira "sphere."
apotropaic: 1883, from Gk. apotropaios "averting evil," from apotrepein "to turn away, avert," from apo- "off, away" + trepein "to turn" (see trope).
heliotrope: "plant which turns its flowers and leaves to the sun," c.1626, from Fr. heliotrope, from L. heliotropium, from Gk. heliotropion, from helios "sun" (see sol) + tropos "turn" (see trope). The word was applied c.1000-1600 in L. form to sunflowers and marigolds.
anisotropic: 1879, a compound variously explained as formed from Gk. anisos "unequal" (from an- "not" + iso- "equal") + tropikos "belonging to a turning," from tropos "a turning" (see trope), or as an- "not" + isotropic.
contrive: early 14c., from O.Fr. controver "to find out, contrive, imagine," from V.L. contropare "to compare" (via a figure of speech), from L. com- "with" + tropus "song, musical mode," from Gk. tropos "figure of speech" (see trope). Sense evolution (in French) was from "invent with ingenuity" to "invent falsely." Related: Contrived (c.1400); contriving (early 14c.); contrivance (1620s).
troop (n.): 1545, "body of soldiers," from M.Fr. troupe, from O.Fr. trope "band of people, company, troop" (13c.), probably from Frank. *throp "assembly, gathering of people" (cf. O.E. ðorp, O.N. thorp "village," see thorp). OED derives the O.Fr. word from L. troppus "flock," which is of unknown origin but may be from the Gmc. source. The verb is attested from 1565, "to assemble;" meaning "to march" is recorded from 1592; that of "to go in great numbers, to flock" is from 1610. Trooper "soldier in the cavalry" is first attested 1640; extended to "mounted policeman" (1858, in Australian) then to "state policeman" (U.S.) by 1911.
troubadour: 1727, from Fr. troubadour "one of a class of lyric poets in southern France, eastern Spain, and northern Italy 11c.-13c.," from O.Prov. trobador, from trobar "to find," earlier "invent a song, compose in verse," probably from V.L. *tropare "compose, sing," especially in the form of tropes, from L. tropus "a song" (see trope). The alternative theory among Fr. etymologists derives the O.Prov. word from a metathesis of L. turbare "to disturb," via a sense of "to turn up." Meanwhile, Arabists posit an origin in Arabic taraba "to sing." General sense of "one who composes or sings verses or ballads" first recorded 1826.