Definition of sill in US English:



  • 1A shelf or slab of stone, wood, or metal at the foot of a window or doorway.

    • ‘With respect to the hallways outside the offices on the fourth, third and second floors, the wooden sills on the windows at the ends of the hallways have had to be replaced.’
    • ‘The entrance door and flanking windows are emphatically Gothic with pointed arches, the doorway framed in granite and the windows with granite sills and lintels.’
    • ‘The building's sweeping windows are equipped with light shelves - deep sills that provide shade and act as reflectors, bouncing light upward to illuminate the interior ceilings.’
    • ‘Lounging on the sill of the opposite window was a figure all dressed in black.’
    • ‘Taking that as a friendly gesture, I leaned closer, but he panicked and scurried into the crack between the window sash and the sill.’
    • ‘Having just removed a concrete set of steps on the front of the house, a small section of sill about two feet is rotted about halfway through.’
    • ‘Features of the Fulton include reconstructed Portland stone features and detailing such as window surrounds, lintels and sills and sliding slash windows.’
    • ‘The house retains its original twin windows and granite sills but is in need of renovation.’
    • ‘The original granite stone sills have been cleaned and repaired, and the original chimney stack at number 3, while no longer in use, has been retained.’
    • ‘Scattered everywhere on sills, shelves, tables, and books are lapidary specimens.’
    • ‘The designer suggested shortening window openings on one side of the kitchen, where sills were only 2 feet from the floor.’
    • ‘This year the stone work lintels, sills and other features were restored and the general area around the church cleaned up.’
    • ‘The crew took extra care and caution around the window dividers and sills - the European hand-blown glass costs thousands of dollars to replicate and replace.’
    • ‘When washing windows, wash sills and cross pieces first.’
    • ‘In fact, the house was repainted last month, and the only part that needed significant scraping and sanding were the sills and trim, which were made of natural wood.’
    • ‘Every penetration of the wall should be flashed, which keeps window heads and sills dry.’
    • ‘Pay special attention to the bottom where the weather strip meets the sill.’
    • ‘The library and its adjacent structure are detailed so that the viewer is gently aware of new sills and metal door frames and an illuminated linear storage unit.’
    • ‘Night deepened, and she sat by the window on the sill.’
    • ‘Painted surface friction points, such as window frames and sills, create paint dust.’
    ledge, bracket, rack
    View synonyms
    1. 1.1 A strong horizontal member at the base of any structure, e.g., in the frame of a motor or rail vehicle.
      • ‘I've got substantial front-end damage - bumper, bonnet, cross-member and sill.’
      • ‘Wide metal door sills and soft-blue ambient lighting welcome you into the car.’
      • ‘Large longitudinal members tie into the side sills through large cross-section cross members, and distribute crash loads throughout the entire structure.’
      • ‘But the sills are lower than the X-bone frame and thus don't impede cabin entry space too much.’
      • ‘Built in 1988, it had doors that dropped down into the high sills, like the window glass in a standard door.’
    2. 1.2Geology A tabular sheet of igneous rock intruded between and parallel with the existing strata.
      Compare with dike
      • ‘The dip slopes are interpreted as separating individual sills near the base of the pluton.’
      • ‘Other leucogranite sheets are intruded as layer-parallel sills along the main foliation.’
      • ‘Several igneous dikes and sills have been intruded into this sedimentary sequence, the largest of which is the Great Whin Sill, a quartz-orthopyroxene dolerite of late Carboniferous age.’
      • ‘This trend continues until in the Odiel River the mafic sills intrude the red mudrock-felsic volcaniclastic facies association.’
      • ‘Clastic dykes do not exclusively intrude sediments; they also intrude granitic rock and mafic sills and are associated with lava flows in volcanic environments.’
    3. 1.3 An underwater ridge or rock ledge extending across the bed of a body of water.
      • ‘Never be afraid to fish the turbulent, white water directly beneath the sill, for the water along the bottom may be quite calm in comparison to the surface.’
      shelf, mantel, mantelpiece, mantelshelf, shelving
      View synonyms


Old English syll, sylle ‘horizontal beam forming a foundation’, of Germanic origin; related to German Schwelle ‘threshold’.