Definitions for "Mullion"
A slender bar or pier which forms the division between the lights of windows, screens, etc.
An upright member of a framing. See Stile.
To furnish with mullions; to divide by mullions.
A mullion is a division between multiple section dampers. The typical mullion will inherently add stiffnessas it is constructed of two jambs fastened together with or without reinforcement.
A mechanism that enables more than one locking point to engage when a single handle is operated Tussendorpel
A narrow structural object between two windowpanes.