aromatic gum resin from a certain type of tree, used anciently as incense and in religious rituals, late 14c., apparently from Old French franc encense, from franc "noble, true" (see frank (adj.)), in this case probably signifying "pure" or "of the highest quality," + encens "incense" (see incense (n.)).[frankincense etymology, frankincense origin, 英语词源]