sill
1 Americannoun
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a horizontal timber, block, or the like serving as a foundation of a wall, house, etc.
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the horizontal piece or member beneath a window, door, or other opening.
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Geology. a tabular body of intrusive igneous rock, ordinarily between beds of sedimentary rocks or layers of volcanic ejecta.
noun
noun
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a shelf at the bottom of a window inside a room
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a horizontal piece along the outside lower member of a window, that throws water clear of the wall below
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the lower horizontal member of a window or door frame
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a continuous horizontal member placed on top of a foundation wall in order to carry a timber framework
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a flat usually horizontal mass of igneous rock, situated between two layers of older sedimentary rock, that was formed by an intrusion of magma
Other Word Forms
- sill-like adjective
- undersill noun
Etymology
Origin of sill
before 900; Middle English sille, Old English syl, sylle; cognate with Low German süll, Old Norse syll; akin to German Schwelle sill
Vocabulary lists containing sill
Earth Science - Middle School
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Earth Science - High School
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Rocks and Minerals - Middle School and High School
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The Red Sea was initially connected from the north to the Mediterranean through a shallow sill.
From Science Daily • Oct. 8, 2025
Often it seems, this cosy spot would appear to be a window sill, as ladybirds can easily squeeze through the small gaps around loose fitting windows.
From BBC • Oct. 7, 2025
“It’s the law,” the not-unkind super replies — though Alex, now 2, can barely sit up, let alone reach the sill.
From New York Times • Apr. 23, 2024
They’re sill exploring options, including possibly lending it to the L.A.
From Los Angeles Times • Mar. 11, 2024
She leaned well out, with her feet off the floor and the sill pressing breathlessly across her stomach.
From "Watership Down: A Novel" by Richard Adams
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
