One of the two small circles of the celestial sphere,
   situated on each side of the equator, at a distance of 23¡ 28/, and
   parallel to it, which the sun just reaches at its greatest declination
   north or south, and from which it turns again toward the equator, the
   northern circle being called the Tropic of Cancer, and the southern the
   Tropic of Capricorn, from the names of the two signs at which they
   touch the ecliptic.