Propylaeum :: Propylaeum (n.) Any court or vestibule before a building or leading into any inclosure.
Propylene :: Propylene (n.) A colorless gaseous hydrocarbon (C3H6) of the ethylene series, having a garlic odor. It occurs in coal gas, and is produced artificially in various ways. Called also propene..
Propylic :: Propylic (a.) Pertaining to, derived from, or containing, propyl; as, propylic alcohol..