lecithin (n.)

fatty substance found in the yolks of eggs (among other places), 1853, from French lécithine (coined 1850 by French pharmacist Theodore N. Gobley), from Greek lekithos "egg yolk," + chemical suffix -ine (2). Greek lekithos is of unknown origin; Beekes writes that, "Because of the suffixes and the meaning, the word is clearly of Pre-Greek origin." Related: Lecithinase.