| Mullion 1. (n.) A slender bar or pier which forms the division between the lights of windows, screens, etc. 2. (n.) An upright member of a framing. See Stile. 3. (v. t.) To furnish with mullions; to divide by mullions. Thesaurus Entries Samson post, baluster, balustrade, banister, doorjamb, doorpost, gatepost, hitching post, jamb, king post, milepost, post, signpost, snubbing post, stanchion, standard, stile, upright |