tropic

(trŏpˈĭk)

1. a. Either of two parallels of latitude on the earth, one 23°27: north of the equator and the other 23°27: south of the equator, representing the points farthest north and south at which the sun can shine directly overhead and constituting the boundaries of the Torrid Zone.
   b. Tropics or tropics The region of the earth's surface lying between these latitudes.
2. Astronomy Either of two corresponding parallels of celestial latitude that are the limits of the apparent northern and southern passages of the sun.

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tropic