[ muhl-yuh n ]
/ ˈmʌl yən /


a vertical member, as of stone or wood, between the lights of a window, the panels in wainscoting, or the like.
one of the radiating bars of a rose window or the like.

verb (used with object)

to furnish with, or to form into divisions by the use of, mullions.

Origin of mullion

First recorded in 1560–70; metathetic variant of monial

Related forms

un·mul·lioned, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for mullions

British Dictionary definitions for mullions


/ (ˈmʌlɪən) /


a vertical member between the casements or panes of a window or the panels of a screen
one of the ribs on a rock face


(tr) to furnish (a window, screen, etc) with mullions

Word Origin for mullion

C16: variant of Middle English munial, from Old French moinel, of unknown origin
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012