sill

/sɪl/

//sɪl// noun

By · According to Wiktionary data (CC BY-SA) ·

"sill" is a 4-letter English headword indexed on PlainSpell.

The verdict

“sill” sits in 20 confusable pairs (corpus #29,086) as a noun. The look-alike neighbours are the real trap.

#29,086
frequency rank, English
6,566
“S” headwords
3
tracked misspellings
20
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - A breast wall; window breast; horizontal brink which forms the base of a window.

Corpus desk

Index EN-sill · sill · English

sill · rank #29,086 · 3 variants · 20 confusables

  • FREQ-MID #29,086
  • LEN-MID 4 letters
  • VOW-1 1 vowel
  • CONFUS-HIGH 20 pairs
  • VAR-LOW 3 variants
  • BOOK-DENSE 6,566
  • PHOTO-FINISH signatories

Nearest frequency peer: signatories (-1 rank slots)

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

Frequency neighbours of confusable “sill”

Peers at similar corpus weight, separate from look-alike pairs below

corpus weight

What this shows Bars place “sill” against nearest ranked English headwords, not a reprint of the confusable-pair desk.

Source FrequencyWords open word-frequency list As of September 3, 2026

Visual similarity to commonly confused words

How many letter changes separate each confused pair (Levenshtein distance, normalized).

sill vs SL
0% similar
sill vs six
50% similar
sill vs sir
50% similar

Source: PlainSpell confusable corpus (Wiktionary, CC BY-SA).

Key facts for sill
PropertyValue
Headwordsill
LanguageEnglish
Part of speechNoun
IPA/sɪl/
Letters4
Frequency rank#29,086
Misspellings tracked3
Confusable pairs20
SourceWiktionary (kaikki.org)

Corpus rank beside confusables of “sill”

Word frequency stretches from the small set of words we reach for constantly (left) out to the long tail barely used once in a while (right).silllands here:

#1#100#1K#10K#100K
← used constantlyrarely used →

Ticks step logarithmically, so each one marks a roughly tenfold drop in how often the word turns up. Same rarity band neighbours include “signatories” (#29,085), “silvery” (#29,087), “sieve” (#29,084). Among 6,566 “S” headwords, “sill” is #29,086. Source: FrequencyWords open word-frequency list.

Easy to mix with look-alikes

The spelling risk for sill is neighbouring look-alikes ("SL", "six", …), not just typos; it is anoun pronounced /sɪl/. Frequency #29,086 among 6,566 “S” headwords. 6 recorded senses keep meaning in play.

Our generated misspelling index lists 3 likely wrong-spelling variants for sill, with forms such as "isll", "slil", and "ssill". Each of these forms differs from the correct spelling by one small edit: a doubled letter, a dropped silent letter, or a substituted vowel. It also participates in 20 confusable-pair relationships, "SL", "six", "sir", and more, a pairing that trips writers up because the two words share enough sound or shape to blur together.

Etymologically, the entry records: From Middle English sille, selle, sülle, from Old English syll, syl (“sill, threshold, foundation, base, basis”), from Proto-Germanic *sulī (“bar, sill”), from Proto-Indo-European *sel-, *swel- (“beam, board, frame, threshold”). Cognate with Scots sil, sill… The correct English form is sill, spelled S-I-L-L.

Definition

  1. 1
    A breast wall; window breast; horizontal brink which forms the base of a window.
  2. 2
    A threshold; horizontal structural member of a building near ground level on a foundation or pilings, or lying on the ground, and bearing the upright portion of a frame; a sill plate.
  3. 3
    A stratum of rock, especially an intrusive layer of igneous rock lying parallel to surrounding strata.
  4. 4
    A threshold or brink across the bottom of a canal lock for the gates to shut against.
  5. 5
    A raised area at the base of the nasal aperture in the skull.
  6. 6
    The inner edge of the bottom of an embrasure.

Recorded use

Wiktionary examples

These source excerpts show how sill appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. She looked out the window resting her elbows on the window sill.
  2. Minor palingenetic magmas probably were generated at this time and intruded the mantling rocks in the form of small sills and apophyses […].

Etymology

From Middle English sille, selle, sülle, from Old English syll, syl (“sill, threshold, foundation, base, basis”), from Proto-Germanic *sulī (“bar, sill”), from Proto-Indo-European *sel-, *swel- (“beam, board, frame, threshold”). Cognate with Scots sil, sill (“balk, beam, floor, sill”), Dutch zulle (“sill”), Low German Sull, Sülle (“threshold, ramp, sill”), German Süll, Sülle (“threshold, sill”), Danish syld (“base of a framework building”), Swedish syll (“joist, cross-tie”), Norwegian syll, Icelandic syll, sylla (“sill”). Related also to German Schwelle ( > Danish svelle), Old Norse svill, Latin silva (“wood, forest”), Ancient Greek ὕλη (húlē).

This word in other languages

alféizar(Español)rebord(Français)Fensterbank(Deutsch)parapeito(Português)

Common misspellings

Also misspelled as:

  • isll
  • slil
  • ssill

Misspelling Pattern Breakdown

How far each generated variant is from the correct spelling of sill - measured in single-character edits (insert, delete, or substitute a letter). Larger bars are easier to catch; one-edit slips are the sneakiest.

isll2slil2ssill1
Edit distance from "sill"

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "sill"?
"sill" is spelled S-I-L-L. The IPA pronunciation is /sɪl/.
What does "sill" mean?
As a noun, "sill" means: A breast wall; window breast; horizontal brink which forms the base of a window.
What words are commonly confused with "sill"?
"sill" is commonly confused with "SL", "six", "sir". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
How do you pronounce "sill"?
The IPA (International Phonetic Alphabet) transcription for "sill" is /sɪl/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "sill"?
From Middle English sille, selle, sülle, from Old English syll, syl (“sill, threshold, foundation, base, basis”), from Proto-Germanic *sulī (“bar, sill”), from Proto-Indo-European *sel-, *swel- (“beam, board, frame, threshold”). Cognate with Scots... See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Similar English words by spelling shape

Same letter count and similar misspelling depth for "sill", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 4 letters (nearest by frequency rank).

SXSW#29,114Togo#29,125pita#29,037peso#29,034

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list