muntin
noun
mun·tin ˈmən-tᵊn 
: a strip separating panes of glass in a sash
Example Sentences
Recent Examples on the Web The kitchen is open to the dining area, and both have glass sliders in which the muntins don’t interfere with the view. 
John Ellement, Boston.com Real Estate, 22 Jan. 2020 Jim initially opposed dark paint on the new large window frame and muntins. Marni Elyse Katz, BostonGlobe.com, 25 July 2019 The new home’s dormers, vertical window muntins, and three-paneled interior doors hark back to Arts and Crafts cottages built in the Poconos in the early 1900s. Sally A. Downey, Philly.com, 12 June 2018 This window is flanked by two rectangular windows with muntins that form elegant hexagonal shapes. Joan Walden, courant.com, 19 Jan. 2018 Above the front door is a Palladian window comprising nine panes that are framed in extra wide muntins of pine. Joan Walden, courant.com, 1 June 2017 Window muntin paint: Palladian Blue (HC-144); benjaminmoore.com. Southern Living, 2 Jan. 2013 Window muntin paint: Palladian Blue (HC-144); benjaminmoore.com. Southern Living, 1 Feb. 2013 See More
John Ellement, Boston.com Real Estate, 22 Jan. 2020 Jim initially opposed dark paint on the new large window frame and muntins. Marni Elyse Katz, BostonGlobe.com, 25 July 2019 The new home’s dormers, vertical window muntins, and three-paneled interior doors hark back to Arts and Crafts cottages built in the Poconos in the early 1900s. Sally A. Downey, Philly.com, 12 June 2018 This window is flanked by two rectangular windows with muntins that form elegant hexagonal shapes. Joan Walden, courant.com, 19 Jan. 2018 Above the front door is a Palladian window comprising nine panes that are framed in extra wide muntins of pine. Joan Walden, courant.com, 1 June 2017 Window muntin paint: Palladian Blue (HC-144); benjaminmoore.com. Southern Living, 2 Jan. 2013 Window muntin paint: Palladian Blue (HC-144); benjaminmoore.com. Southern Living, 1 Feb. 2013 See More Word History
Etymology
alteration of montant vertical dividing bar, from French, from present participle of monter to rise — more at mount
First Known Use
1774, in the meaning defined above