citron (n.) Look up citron at Dictionary.com
late 14c., also citrine (early 15c.), from Old French citron "citron, lemon" (14c.), possibly from Old Provençal citron, from Latin citrus and influenced by lemon; or else from augmentative of Latin *citrum, related to citrus "citron tree," citreum (malum) "citron" (see citrus). Apparently the only citrus fruit known to the Greeks and Romans.