12 letters · 19 points in Scrabble
noun an orienting response to the sun
originEtymology tree Proto-Indo-European *sóh₂wl̥ Proto-Indo-European *sh₂wél(i)yos Proto-Hellenic *hāwélios Ancient Greek ἥλῐος (hḗlĭos) English helio- English -tropism English heliotropism From helio- + -tropism.
Etymology from Wiktionary, CC BY-SA 3.0