Tropic

noun
1.
Geography.

either of two corresponding parallels of latitude on the terrestrial globe, one (tropic of Cancer) about 23½° N, and the other (tropic of Capricorn) about 23½° S of the equator, being the boundaries of the Torrid Zone.
the tropics, the regions lying between and near these parallels of latitude; the Torrid Zone and neighboring regions.

2.
Astronomy. either of two circles on the celestial sphere, one lying in the same plane as the tropic of Cancer, the other in the same plane as the tropic of Capricorn.
adjective
3.
of, pertaining to, characteristic of, or occurring in the tropics; tropical:
romance under the tropic skies of Old Mexico.
1.
a combining form with the meanings “turned toward, with an orientation toward” that specified by the initial element (geotropic), “having an affinity for, affecting” what is specified (lipotropic; neurotropic; psychotropic), “affecting the activity of, maintaining” a specified organ (gonadotropic).
noun
1.
(sometimes capital) either of the parallel lines of latitude at about 231/2°N (tropic of Cancer) and 231/2°S (tropic of Capricorn) of the equator
2.
(often capital) the tropics, that part of the earth’s surface between the tropics of Cancer and Capricorn; the Torrid Zone
3.
(astronomy) either of the two parallel circles on the celestial sphere having the same latitudes and names as the corresponding lines on the earth
adjective
4.
a less common word for tropical
combining form
1.
turning or developing in response to a certain stimulus: heliotropic

-tropic suff.
Affecting or attracted to something specified: gonadotropic.
tropic
(trŏp’ĭk)

Either of the two parallels of latitude representing the points farthest north and south at which the Sun can shine directly overhead. The northern tropic is the Tropic of Cancer and the southern one is the Tropic of Capricorn.

tropics. The region of the Earth lying between these latitudes. The tropics are generally the warmest and most humid region of the Earth. Also called Torrid Zone.