The imaginary line marking the upper end of the lower body of an automobile, running just below the bottoms of the windows(noun)
A beltway: a circular expressway around a city(noun)
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Use "beltline" in a sentence
"Bring them visually down to size with a "beltline" - a horizontal division in the wall space that comes from using moulding, wainscoting or tile in the middle."
"As the result of a discussion last evening in regard to the time required to walk around the beltline, that is, starting at a given point in Lewiston and walking down Main Street to Auburn, thence to New Auburn returning to the starting point via Cedar and Lisbon streets, a trial walk was taken."
"Apart from the beltline which is a bit high for my taste (though that is something all cars seem to suffer from lately), they managed to modernize the design pretty well."