a parallel of latitude at about 23½° north of the equator. Also called tropic of Cancer
a parallel of latitude at about 23½° south of the equator. Also called tropic of Capricorn
(the tropics) the region between these two parallels
in astronomy, either of the two corresponding parallel celestial latitudes that are the apparent northern and southern limits of the passage of the sun
[Middle English, via Latin from Greek tropikos, from tropē a route, a turning, from trepein to turn]