13 letters · 23 points in Scrabble
noun (chemistry) the relation between the quantities of substances that take part in a reaction or form a compound (typically a ratio of whole integers)
originCoined as German Stöchiometrie by Jeremias Benjamin Richter in 1792. From Ancient Greek στοιχεῖον (stoikheîon, “element”) + -metry.
Etymology from Wiktionary, CC BY-SA 3.0