the word 'tropics' originates from the greek 'tropikos', meaning "pertaining to a turn." this refers to the turning points of the sun at the solstices, specifically the points where the sun appears to stop moving north or south and turns back. these celestial turning points were used to define the lines of latitude—the tropic of cancer and the tropic of capricorn. consequently, the plural form 'tropics' came to denote the geographical region between these two lines, where the sun is directly overhead at some point during the year, leading to its association with a perpetually hot climate.

Structure: trop (turn) + ics (plural noun suffix denoting area/study) trop (from greek 'tropos', meaning a turn, change, or way; via latin 'tropicus') + ics (from greek '-ikos', a suffix forming adjectives and nouns, often used in english to denote a field, area, or set of things).