tropic¹ ◙ noun 1. the parallel of latitude 23°26' north tropic of Cancer or south tropic of Capricorn of the equator • 回归线（纬度均为２３°26′的赤道北、南两条平行线： 北回归线 [tropic or Caucer] 和南回归线 [tropic or Capricorn] ） [Astronomy] each of two corresponding circles on the celestial sphere where the sun appears to turn after reaching its greatest declination, marking the northern and southern limits of the ecliptic • [天文] 天球的回归线 (the tropics)the region between the tropics of Cancer and Capricorn • 热带（北、南回归线之间的地带） ◙ adjective 1. another term for tropical (in sense 1) • 同tropical[义项1]
【语源】
1. late Middle English (denoting the point on the ecliptic reached by the sun at the solstice): via Latin from Greek tropikos, from tropē 'turning', from trepein 'to turn'tropic² ◙ adjective 1. [Biology] relating to, consisting of, or exhibiting tropism • [生] 向性的；亲…的 2. [Physiology] . variant spelling of trophic • [生理] 同trophic