9 letters · 13 points in Scrabble
adjective invariant with respect to direction
originFrom iso- + -tropic, from Ancient Greek ἴσος (ísos, “equal”) + τροπικός (tropikós, “of or pertaining to a turn or change; or the solstice; or a trope or figure; tropic; tropical; etc.”).
Etymology from Wiktionary, CC BY-SA 3.0