HTML Entity for Not Element Of (∉)
What You'll Learn
How to display the Not Element Of symbol (∉) in HTML using named, hexadecimal, decimal, and CSS escape methods. This set-membership operator states that an element is not in a set (e.g. x ∉ A means x is not an element of set A).
This character is U+2209 (NOT AN ELEMENT OF) in the Mathematical Operators block (U+2200–U+22FF). Render it with the named entity ∉, ∉, ∉, or CSS escape \2209. Compare with Element Of (∈, ∈).
⚡ Quick Reference — Not Element Of
U+2209Mathematical Operators
∉Hexadecimal reference
∉Decimal reference
∉HTML5 named entity for U+2209
Name Value
──────────── ──────────
Unicode U+2209
Hex code ∉
HTML code ∉
Named entity ∉
CSS code \2209
Meaning Not an element of
Related U+2208 = element of (∈, ∈)
U+220B = contains as member (∋, ∋)
U+2260 = not equal (≠, ≠)
Block Mathematical Operators (U+2200–U+22FF)Complete HTML Example
A simple example showing ∉ using hexadecimal code, decimal HTML code, the named entity, and a CSS content escape:
<!DOCTYPE html>
<html>
<head>
<style>
#point::after{
content: "\2209";
}
</style>
</head>
<body>
<p>Symbol (hex): ∉</p>
<p>Symbol (decimal): ∉</p>
<p>Symbol (named): ∉</p>
<p id="point">Symbol (CSS): </p>
</body>
</html>🌐 Browser Support
U+2209 is widely supported wherever Unicode Mathematical Operators render correctly:
👀 Live Preview
See ∉ in set theory and membership contexts:
🧠 How It Works
Named Entity
∉ is the HTML named entity for U+2209—the most readable choice when writing set-membership markup.
Hexadecimal Code
∉ uses the Unicode hexadecimal value 2209 to display the not-element-of symbol.
Decimal HTML Code
∉ uses the decimal Unicode value 8713 to display the same character.
CSS Entity
\2209 is used in CSS stylesheets, particularly in the content property of pseudo-elements like ::before and ::after.
Same visual result
All four methods produce: ∉. Unicode U+2209 in Mathematical Operators (U+2200–U+22FF).
Use Cases
The ∉ symbol (∉) is commonly used in:
Expressing that an element is not a member of a set.
Discrete math textbooks, papers, and lecture notes published as HTML.
Formal definitions and proof steps involving set membership.
Data structures and algorithms courses covering sets and collections.
Interactive math modules with web-based notation.
Unicode charts and HTML entity documentation for math symbols.
💡 Best Practices
Do
- Use
∉for readable set-membership markup - Pair ∉ with plain-language description on first use
- Distinguish from ∈ (element of) and ≠ (not equal)
- Add
aria-labelfor standalone relation symbols - Serve pages with UTF-8 (
<meta charset="utf-8">)
Don’t
- Confuse ∉ (
∉) with ∈ (∈) - Use ∉ when you mean strict inequality (≠,
≠) - Use padded Unicode notation like U+02209—the correct value is
U+2209 - Put CSS escape
\2209in HTML text nodes - Use
\02209in CSS—the correct escape is\2209
Key Takeaways
Three HTML references plus CSS all render ∉
∉ ∉ ∉For CSS stylesheets, use the escape in the content property
\2209Unicode U+2209 — NOT AN ELEMENT OF
Mathematical Operators block (U+2200–U+22FF)
∉ is the preferred named entity for readable source markup
❓ Frequently Asked Questions
∉ (named), ∉ (hex), ∉ (decimal), or \2209 in CSS content. All produce ∉.U+2209 (NOT AN ELEMENT OF). Mathematical Operators block (U+2200–U+22FF). Hex 2209, decimal 8713. Named entity: ∉.∉) means an element is not in a set. ≠ (≠) means two values are not equal. They apply to different kinds of mathematical statements.∉ is the named HTML entity for U+2209 and is the most readable option in source markup.Explore More HTML Entities!
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