Definition of tropic

• a. - Of, pertaining to, or designating, an acid obtained from atropine and certain other alkaloids, as a white crystalline substance slightly soluble in water.
• n. - 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.
• n. - One of the two parallels of terrestrial latitude corresponding to the celestial tropics, and called by the same names.
• n. - The region lying between these parallels of latitude, or near them on either side.
• a. - Of or pertaining to the tropics; tropical.