9 letters · 15 points in Scrabble
originFrom ideo- + -phone. James F. Fordyce (The Ideophone as a Phonosemantic Class: The Case of Yoruba, in Current approaches to African linguistics, Ivan R. Dihoff (ed.), page 263) credits C. M. Doke with introducing the term in 1935.
Etymology from Wiktionary, CC BY-SA 3.0