Windowsill or Window Sill: Which Is Correct?

Windowsill is the standard one-word spelling for the ledge at the bottom of a window. You may occasionally see window sill as two words, but windowsill is the usual form in modern English. Because it is an established compound noun, the closed spelling is the natural choice in most everyday and formal writing.

Quick Answer:

Use “windowsill” as the standard one-word noun for a window ledge. Window sill may appear as two words, while window-sill is occasionally used with a hyphen.

The cat is sitting on the windowsill.

Preferred form: windowsill = one word

Windowsill vs. Window Sill

Why Is “Windowsill” One Word?

Windowsill is a compound noun formed from window + sill. Like bookshelf, doorway, and bedroom, it has become an established single word.

So, when naming the ledge at the bottom of a window, write windowsill rather than splitting the compound.

Common Mistakes

❌ The cat sat on the window sill.
✅ The cat sat on the windowsill.

❌ She placed a plant on the window-sill.
✅ She placed a plant on the windowsill.

✅ The windowsill needs cleaning.

Pronunciation

Windowsill is pronounced as one word, with the main stress on the first part. The final part sounds like sill.

Six Examples

1. The cat curled up on the windowsill.
2. She placed a small plant on the sunny windowsill.
3. Rainwater collected along the windowsill.
4. He found an old coin on the windowsill.
5. The children decorated the windowsill with candles.
6. A sparrow landed briefly on the windowsill.

Easy Memory Trick

Think:

window + sill = windowsill

When the two words name the window ledge, keep them together.

Mini Quiz

1. Which spelling is the standard compound noun?
A. Window sill
B. Windowsill
C. Window-sill
D. Windowsil

2. What does “windowsill” refer to?
A. The glass in a window
B. The ledge at the bottom of a window
C. The curtain beside a window
D. The wall above a window

3. Complete the sentence: “The plant is sitting on the □.”
A. window sill
B. windowsill
C. window-sill
D. windowsile

4. Which sentence is correct?
A. The bird landed on the windowsill.
B. The bird landed on the window-sill.
C. The bird landed on the windowsile.
D. The bird landed on the windowsil.

5. Why is “windowsill” written as one word?
A. It is an established compound noun.
B. It is a verb.
C. It is an abbreviation.
D. It is a proper name.

Answers: 1-B, 2-B, 3-B, 4-A, 5-A

FAQs

Is it “windowsill” or “window sill”?

Windowsill is the standard one-word form. The open form may appear, but it is not the usual modern spelling.

Is “window-sill” correct?

You may occasionally see the hyphenated form, but windowsill is the preferred modern form.

Is windowsill one word?

Yes. Windowsill is normally written as one word.

What is a windowsill used for?

A windowsill is the ledge at the bottom of a window and can provide a surface for small objects such as plants or decorations.

Conclusion

Windowsill is the standard one-word spelling. Although window sill and window-sill may appear, windowsill is the clearest and most natural choice in modern writing.

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William Strunk

William Strunk is a respected authority on English grammar, usage, and writing style, known for his influential work The Elements of Style. At EduNexxa, his focus is on clear, concise, and effective English.