14 letters · 24 points in Scrabble
originFrom photo- (from the combining form φωτω- (phōtō-) of Ancient Greek φῶς (phôs, “light”)) + autotroph, from auto- (from Ancient Greek αὐτο- (auto-, “self-”)) + -troph (from Ancient Greek τροφή (trophḗ, “nourishment”)).
Etymology from Wiktionary, CC BY-SA 3.0