From Longman Dictionary of Contemporary Englishwindowsillwin‧dow‧sill /ˈwɪndəʊˌsɪl $ -doʊ-/ (also window ledge) noun [countable] DHa shelf fixed along the bottom of a window
Examples from the Corpus
windowsill• You can have an instant garden for a windowsill, balcony, roof terrace, or even your doorstep.• Here and there the head of a child was seen peering over a windowsill.• Vermilion, cobalt and acid yellow melt across a sofa, a wall, a windowsill.• And there, beyond the books on the windowsill, her floods, transforming the world like the eye in love.• I reached for the brick on the windowsill.• I am going to put it on the windowsill.• He swung his legs over the windowsill and for an instant his torso seemed to disappear into the darkness inside. 