sill

noun

ˈsil 

1

: a horizontal piece (such as a timber) that forms the lowest member or one of the lowest members of a framework or supporting structure: such as

a

: the horizontal member at the base of a window

b

: the threshold of a door

2

: a tabular body of igneous rock injected while molten between sedimentary or volcanic beds or along foliation planes of metamorphic rocks

3

: a submerged ridge at relatively shallow depth separating the basins of two bodies of water

Examples of sill in a Sentence

Recent Examples on the Web

Indoor success requires a bright window sill and constant monitoring of the soil moisture levels. —Arricca Elin Sansone, Southern Living, 29 Jan. 2025

To prevent this from continuing, a group of scientists in 2018 proposed artificially increasing the height of the iceberg-snagging sill. —Elizabeth Kolbert, The New Yorker, 7 Oct. 2024

This set of three rectangular planters are designed to be used on window sills and are great for growing herbs. —Rachel Ahrnsen, Better Homes & Gardens, 3 Jan. 2025

Plus, many people described using it on baseboards, window sills, ceiling fans, molding, and more. —Shea Simmons, People.com, 5 Nov. 2024

Word History

Etymology

Middle English sille, from Old English syll; akin to Old High German swelli beam, threshold

First Known Use

before the 12th century, in the meaning defined at sense 1

Kids Definition

sill

noun

ˈsil 

1

: a horizontal piece (as a timber) that forms the lowest part of a supporting structure: as

a

: the horizontal piece at the base of a window

b

: the timber or stone at the foot of a door : threshold

2

: a flat mass of igneous rock injected while melted between other rocks