intertropical comes from inter- ('between') + tropical, from tropic, from Latin tropicus, from Greek tropikos ('of the turning'), from tropos ('a turn'), from trepein ('to turn'). Morphologically, the prefixed shape matters: the initial element belongs to the recorded formation and helps explain the modern form's surface analysis. In present English, the adjective sense is "situated or occurring between the tropics", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as tropic, tropical, and tropics. Its semantic neighborhood includes equatorial and tropical, which helps locate the modern sense without adding a separate etymological claim. The named historical forms include Latin inter- and Ancient Greek tropikós.