mullion Meaning, Definition & Usage

  1. noun a nonstructural vertical strip between the casements or panes of a window (or the panels of a screen)

WordNet

Mul"lion noun
Etymology
A corruption of munnion, F. moignon stump of an amputated limb, stump, OF. moing mutilated; cf. Armor. moñ, mouñ, mank, monk, and also L. mancus maimed.
Definitions
  1. (Arch.) (a) A slender bar or pier which forms the division between the lights of windows, screens, etc. (b) An upright member of a framing. See Stile.
Mul"lion transitive verb
Definitions
  1. To furnish with mullions; to divide by mullions.

Webster 1913