Complement (∁) is the Unicode character at U+2201 in the Mathematical Operators block. It is used in math and set-theory notation for a complement-style symbol — a spacing glyph, not a combining mark.
Remember
Character ∁
Unicode U+2201
Hex entity ∁
Decimal ∁
Named entity ∁
CSS escape \2201
Not the same ∅ U+2205 · ¬ U+00AC
All of these produce the same glyph: ∁. Prefer ∁ or a typed ∁ in hand-written HTML; use numeric forms when generating markup.
One page that shows Complement with the named entity, hex entity, decimal entity, CSS escape, and a typed character. Use View Output or open the live editor.
Named + Hex + Decimal + CSS + Typed
Five ways to produce ∁ in a single document.
html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Complement (∁) in HTML</title>
<style>
#point::after {
content: "\2201";
}
</style>
</head>
<body>
<p>Complement using Named Entity: ∁</p>
<p>Complement using Hex Code: ∁</p>
<p>Complement using HTML Code: ∁</p>
<p id="point">Complement using CSS Entity: </p>
<p>Typed directly: ∁</p>
</body>
</html>
Complement using Named Entity: ∁
Complement using Hex Code: ∁
Complement using HTML Code: ∁
Complement using CSS Entity: ∁
Typed directly: ∁
How It Works
1. Named:∁ is the HTML5 named reference for U+2201 → ∁.
2. Hex:U+2201 → ∁ in HTML. Same glyph as the named form.
3. Decimal: same code point as 8705 → ∁. Same result as hex.
4. CSS: use \2201 in content (not an HTML entity). #point::after appends that ∁ after the paragraph text.
5. Typed: in a UTF-8 page you can paste ∁ directly. All five lines show the same glyph.
Pitfalls & Tips
Common mistakes when working with Complement entities.
Named
Use ∁
The HTML5 named form is ∁. There is no ∁ alias in HTML5.
∅ vs ∁
Not empty set
∅ is empty set (U+2205). ∁ is complement (U+2201). Different symbols for different ideas.
¬ vs ∁
Not logical not
¬ (U+00AC) is not-sign for logic. Do not use it as a stand-in for set complement ∁.
CSS vs HTML
Do not mix escapes
\2201 belongs in CSS. ∁ / ∁ / ∁ belong in HTML.
Fonts
Math font coverage
Some fonts omit U+2201. Prefer a font with Mathematical Operators coverage for display.
Semicolon
End references
Always finish with ; — write ∁ and ∁, not bare forms.
Compatibility
Browser Support
Complement (U+2201) and its entity forms (∁, ∁, ∁, CSS \\2201) are supported in all mainstream browsers. Visible glyphs depend on font coverage.
✓ Universal support
Complement (∁)
Encode with named, hex, decimal, CSS escape, or type the character — same glyph everywhere encoding is supported.
100%Browser coverage
Google ChromeSupported
Yes
Microsoft EdgeSupported
Yes
Mozilla FirefoxSupported
Yes
Apple SafariSupported
Yes
OperaSupported
Yes
Internet ExplorerAll versions
Yes
U+2201 / entitiesFull support
Bottom line: Prefer ∁ or typed ∁ in HTML. Use \\2201 only inside CSS content. Do not confuse with empty set ∅ or not-sign ¬.
Remember
Key Takeaways
Unicode: complement is U+2201 (decimal 8705) — glyph ∁.
HTML: use ∁, ∁, ∁, or type ∁.
CSS: use \2201 inside content for generated text.
Watch out:∁ ≠ ∅ ≠ ¬.
One line:U+2201 → ∁ / ∁ / CSS \2201 / type ∁.
Frequently Asked Questions
Use ∁ (hex), ∁ (decimal), ∁ (named), or the CSS escape \2201 in the content property. All render ∁. You can also paste ∁ directly when your file is UTF-8.
U+2201 (hex 2201, decimal 8705). It belongs to the Mathematical Operators block and is used for complement notation in math and set theory.
Yes. ∁ is the HTML5 named reference for ∁. Numeric forms ∁ and ∁ also work.
Use it in math or set-theory pages that need the complement glyph. In plain English prose, writing “complement” as a word is clearer for beginners.
HTML entities (∁, ∁, or ∁) go in markup. The CSS escape \2201 goes in stylesheet strings (usually content on ::before/::after).
∁ (U+2201 / ∁) is COMPLEMENT. ∅ (U+2205) is EMPTY SET. ¬ (U+00AC) is NOT SIGN — logical negation, not set complement.
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Did you know?
Complement is Unicode U+2201 (decimal 8705) — glyph ∁ in the Mathematical Operators block. HTML named reference is ∁. It is used in set theory and math texts for complement-style notation. It is not empty set ∅ (U+2205) and not not-sign ¬ (U+00AC).
