From Longman Dictionary of Contemporary Englishmullionmul‧lion /ˈmʌljən/ noun [countable] technical TBBDHa vertical piece of stone, metal, or wood between two pieces of glass in a window —mullioned adjective
Examples from the Corpus
mullion• In section each mullion is an asymmetric oval, tapering at one end.• The use of ground anchors in tension and the glazing mullions as compression members resolves the forces from the cable-net.• Thatched roof, two storeys, the second had more mullion windows hunched inside the thatch.• Plasteel mullions divided the narrow, high lancet windows of stained armour-glass.• The gable wall structure consists of a series of fabricated steel mullions at 3.6m centres.• She was taken to a comfortable bedroom with stone mullions and changed into clothes appropriate for the occasion.• Then he saw the mullion windows were open.• Store removed material well away from the work area 5 Use a general-purpose saw to cut through mullions and transoms. 