sill

Etymology

It is inherited from Middle English sille,^[2][3][4] inherited from Old English syll, also sylle,^[5][6][7] inherited from Proto-Germanic *suljō.^[3][8] Its cognates include Middle Low German sulle, Middle Dutch sulle, Old Norse svill and syll, Swedish syll, Danish syld (“framework of a building”), and Old High German swelli, the source of German Schwelle (“threshold”).^[5][3][9][4] The OED finds the relationship of these forms to one another, and to Gothic 𐌲𐌰𐍃𐌿𐌻𐌾𐌰𐌽 (gasuljan, “to found”) and Latin solea (“the foundation of a wattled wall”), unclear.^[5] Etymonline and Barnhart connect it, perhaps, with Proto-Indo-European *swel- (“post, board”),^[3][8] and Klein and Holthausen compare Ancient Greek σελίς (selís, “plank, rower's bench”) and σέλμα (sélma, “beam, deck”).^[4][10][11]

Earliest recorded meaning

A strong horizontal beam serving as the foundation of a wall or other structure: Old English, in King Ælfred's translation of Gregory's Pastoral Care.^[5] Barnhart dates Old English syll to about 725, in Beowulf,^[8] and Bosworth-Toller glosses it as a beam serving as a foundation or support, and figuratively a basis.^[7]

Semantic evolution

Ayto notes that the word first meant the foundation of a wall and was not used for the base of a window frame until the 15th century;^[12] the OED's first record of the window sense is from 1428.^[5][3] The Middle English form sille is found about 1390, in Sir Gawain and the Green Knight,^[8] and Chaucer used it once for a floor.^[13] From 1600 it was the threshold of a door,^[5][3] and Johnson (1755) defined it only as "the timber or stone at the foot of the door".^[14] Later technical uses followed: in mining (1747), for the timber at the bottom of a dock or lock entrance against which the gates close (1789), for a bed of rock (1794), which geologists now use for a sheet of igneous rock forced between older layers,^[5][3] and for a ridge on the sea bed separating two bodies of water (1933).^[5] In American and dialect use it was also a lower frame timber of a cart or railway car (1874), and later of a motor vehicle (1959).^[5]

Timeline

• Old English – a beam forming the foundation of a wall.^[5][7]
• c. 1390 – the Middle English form sille, in Sir Gawain and the Green Knight.^[8]
• 1428 – the lower horizontal part of a window opening.^[5][3]
• 1552 – verb, to furnish with a sill.^[5]
• 1600 – the threshold of a door.^[5][3]
• 1774 – a kind of clay found among coal seams.^[5]
• 1789 – the timber at the bottom of a lock or dock entrance.^[5]
• 1794 – a bed or layer of rock, later a sheet of intrusive igneous rock.^[5][3]
• 1874 – a lower frame timber of a cart or railway car.^[5]
• 1933 – a ridge on the sea bed separating two bodies of water.^[5]

Meanings

Noun

1. The horizontal piece of wood or stone at the base of a window opening; a windowsill: She left the pie to cool on the sill.^[15][11][5]
2. The threshold of a door, or the lower horizontal part of a door frame.^[11][15][5]
3. A horizontal beam forming the lowest part of a framework, as of a house set on a foundation wall, a bridge or the body of a vehicle.^[11][15][5]
4. (geology) A flat sheet of igneous rock forced as magma between older layers of rock.^[15][5]
5. A ridge on the sea bed that separates two bodies of water.^[5]

Verb

1. To provide with a sill.^[11][5]

Word family

• sill-like
• sillcock
• undersill
• doorsill
• groundsill
• mudsill
• windowsill

Related words

• thill

Usage notes

Sill is also an old dialect variant of thill, a shaft of a cart, recorded from 1787 in Grose's Provincial Glossary;^[5][6] Merriam-Webster Unabridged marks it archaic.^[11] In dialects from Scotland and northern England to the Midlands and East Anglia, sill meant the threshold of a door.^[16] Merriam-Webster Unabridged and the Shorter Oxford record the rare spelling cill.^[11][6]

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
3. ^ a b c d e f g h i j Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
5. ^ a b c d e f g h i j k l m n o p q r s t u v w x y Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
6. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
7. ^ a b c Bosworth, Joseph; Toller, T. Northcote (1898), An Anglo-Saxon Dictionary, Oxford: Clarendon Press; Toller, T. Northcote (1921), Supplement
8. ^ a b c d e Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
9. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
10. ^ Holthausen, Ferdinand (1934), Altenglisches etymologisches Wörterbuch, Heidelberg: Carl Winter
11. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
12. ^ Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
13. ^ Benson, Larry D., Glossarial Concordance to Middle English (Chaucer, Gower), Johns Hopkins University, github.com/jhu-digital-manuscripts/gcme
14. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
15. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins
16. ^ Wright, Joseph, ed. (1898–1905), The English Dialect Dictionary, 6 vols., Oxford: Henry Frowde; via EDD Online 4.0, University of Innsbruck (CC BY 4.0)