An Etymological Dictionary of Astronomy and Astrophysics

Either of the two parallels of latitude on Earth at which the Sun appears overhead at the → summer and → winter solstices each year: → Tropic of Cancer, → Tropic of Capricorn . The tropics lie at latitudes 23°26’, north and south, an angle defined by the Earth’s → axial inclination.

Etymology (EN): M.E., from L. tropicus, from Gk. tropikos “of or pertaining to a turn or change; of or pertaining to to the turn of the Sun’s apparent motion at solstice,” from trope “a turning.”

Etymology (PE): Hurgard, literally “Sun’s turning,” from hur, → Sun,

• gard “turning, changing,” from gardidan “to turn, to change;” Mid.Pers. vartitan; Av. varət- “to turn, revolve;” Skt. vrt- “to turn, roll,” vartate “it turns round, rolls;” L. vertere “to turn;” O.H.G. werden “to become;” PIE base *wer- “to turn, bend.”