Source : Webster's Revised Unabridged Dictionary (1913)

Propylon \Prop"y*lon\, n.; pl. {Propyla}. [NL., from Gr. ?; ?
   before + ? a gate.] (Anc. Arch.)
   The porch, vestibule, or entrance of an edifice.

Source : WordNet®

propyla
     See {propylon}