parting strip

American  

noun

1. a strip, as of wood, used to keep two parts separated, as one in each side of the frame of a window to keep the sashes apart when lowered or raised.

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parting strip British  

noun

1. a thin strip of wood, metal, etc, used to separate two adjoining materials

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Example Sentences

Then, on at least one side of the window, remove the parting strip that separates the upper and lower sashes.

From Washington Post

The parting strip is a thin piece of wood that fits into a groove, so it isn’t easy to pry out.

From Washington Post