Definition of mullion in English:



  • A vertical bar between the panes of glass in a window.

    Compare with transom
    • ‘Vertical and horizontal extruded aluminum mullions serve as the structural members.’
    • ‘The mullions of the interior window walls line up with those of the exterior, creating a seamless appearance.’
    • ‘The houses are mainly terraced, built in Yorkshire stone with traditional Victorian sash windows, stone mullions and slate roofs.’
    • ‘Simple details make the space special: window mullions are spaced so they don't block the view of Peter, who is tall, or Betsy, who is shorter.’
    • ‘Naturalism could, however, conflict with the demands of the setting, as in the stained glass at Fairford church, where the stone mullions cut across compositions designed as a unity.’
    • ‘It was just possible to see them both at the same time by standing in the Garden Court and viewing the Ingres at an angle through the mullions and glass panes of a doorway, but a little back-and-forthing proved more rewarding.’
    • ‘The delicate glass facades of the south and west sides with their trussed glass mullions and oiled oak transoms are surrounded by tall, elegant and immensely thin colonnades.’
    • ‘The pavilion's all glass structure, with its transparent mullions and ceiling joists, is perhaps no longer very radical: we have had several varieties of such transparent sheds over the last decade.’
    • ‘Externally what catch the eye are the closely spaced vertical timbers (close studding), quatrefoil decoration, and windows with moulded timber mullions.’
    • ‘Both walls have fixed glazing with custom-built mullions and transoms.’
    • ‘There are several well dressed blocks of lime stone scattered about the graveyard, one of them being part of the cap of the ogee-headed window divided by a mullion.’
    • ‘In this work, appropriately titled Across the Street, a window with soot-black mullions gives onto a view of geometric shrubbery in the near distance, beyond which the built landscape stacks in blocks and meets the sky.’
    • ‘The family has no thought of moving, but Mrs Huyshe-Shire fears for the historic stained glass as the state of the mullions gets worse.’
    • ‘The clear glass skin of the banking and ATM hall is held in place by slim vertical mullions, emphasizing its sleek, diaphanous quality.’
    • ‘The configuration and mullion patterns of several of the windows also seemed to evoke Marion's hand.’
    • ‘Glass manufacturers and structural engineers are testing not only new glass interlayers, but also new window systems, including mullions, frames and anchors.’
    • ‘The views from this space are hacked up with ribbon windows that are actually thin vertical pieces of glass separated with heavy mullions that frustrate your attempts to enjoy the sweeping view.’
    • ‘Unusually thin mullions span the tall space, turning it into a gigantic glass jigsaw puzzle recomposing the view.’
    • ‘The vertical mullions and stainless steel double chimney recall the pine trees that surround and almost engulf the house.’


Mid 16th century.