∥ Parallel (relation). Synonym: \parallel.

ℵ Aleph, transfinite cardinal (ordinary).

α Lowercase Greek letter alpha (ordinary).

⨿ Disjoint union (binary)

∠ Geometric angle (ordinary). Similar: less-than sign < and angle bracket \langle.

≈ Almost equal to (relation).

∗ Asterisk operator, convolution, six-pointed (binary). Synonym: *, which is often a superscript or subscript, as in the Kleene star. Similar: \star, which is five-pointed, and is sometimes used as a general binary operation, and sometimes reserved for cross-correlation.

≍ Asymptotically equivalent (relation).

\ Backslash (ordinary). Similar: set minus \setminus, and \textbackslash for backslash outside of math mode.

β Lowercase Greek letter beta (ordinary).

⋂ Variable-sized, or n-ary, intersection (operator). Similar: binary intersection \cap.

⚪ Circle, larger (binary). Similar: function composition \circ.

⋃ Variable-sized, or n-ary, union (operator). Similar: binary union \cup.

⨀ Variable-sized, or n-ary, circled dot operator (operator).

⨁ Variable-sized, or n-ary, circled plus operator (operator).

⨂ Variable-sized, or n-ary, circled times operator (operator).

▽ Variable-sized, or n-ary, open triangle pointing down (binary). Synonym: \varbigtriangledown.

△ Variable-sized, or n-ary, open triangle pointing up (binary). Synonym: \varbigtriangleup.

⨆ Variable-sized, or n-ary, square union (operator).

⨄ Variable-sized, or n-ary, union operator with a plus (operator). (Note that the name has only one p.)

⋁ Variable-sized, or n-ary, logical-or (operator).

⋀ Variable-sized, or n-ary, logical-and (operator).

⊥ Up tack, bottom, least element of a partially ordered set, or a contradiction (ordinary). See also \top.

⋈ Natural join of two relations (relation).

□ Modal operator for necessity; square open box (ordinary). Not available in plain TeX. In LaTeX you need to load the amssymb package.

• Bullet (binary). Similar: multiplication dot \cdot.

∩ Intersection of two sets (binary). Similar: variable-sized operator \bigcap.

⋅ Multiplication (binary). Similar: Bullet dot \bullet.

χ Lowercase Greek chi (ordinary).

∘ Function composition, ring operator (binary). Similar: variable-sized operator \bigcirc.

♣ Club card suit (ordinary).

∁ Set complement, used as a superscript as in $S^\complement$ (ordinary). Not available in plain TeX. In LaTeX you need to load the amssymb package. Also used: $S^{\mathsf{c}}$ or $\bar{S}$.

≅ Congruent (relation).

∐ Coproduct (operator).

∪ Union of two sets (binary). Similar: variable-sized operator \bigcup.

† Dagger relation (binary).

⊣ Dash with vertical, reversed turnstile (relation). Similar: turnstile \vdash.

‡ Double dagger relation (binary).

Δ Greek uppercase delta, used for increment (ordinary).

δ Greek lowercase delta (ordinary).

◇ Large diamond operator (ordinary). Not available in plain TeX. In LaTeX you need to load the amssymb package.

⋄ Diamond operator (binary). Similar: large diamond \Diamond, circle bullet \bullet.

♢ Diamond card suit (ordinary).

÷ Division sign (binary).

≐ Approaches the limit (relation). Similar: geometrically equal to \Doteq.

↓ Down arrow, converges (relation). Similar: \Downarrow double line down arrow.

⇓ Double line down arrow (relation). Similar: \downarrow single line down arrow.

ℓ Lowercase cursive letter l (ordinary).

∅ Empty set symbol (ordinary). The variant form is \varnothing.

ϵ Lowercase lunate epsilon (ordinary). Similar to Greek text letter. More widely used in mathematics is the script small letter epsilon \varepsilon ε. Related: the set membership relation \in ∈.

≡ Equivalence (relation).

η Lowercase Greek letter (ordinary).

∃ Existential quantifier (ordinary).

♭ Musical flat (ordinary).

∀ Universal quantifier (ordinary).

⌢ Downward curving arc (ordinary).

Γ uppercase Greek letter (ordinary).

γ Lowercase Greek letter (ordinary).

≥ Greater than or equal to (relation). This is a synonym for \geq.

≥ Greater than or equal to (relation). This is a synonym for \ge.

← Is assigned the value (relation). Synonym: \leftarrow.

≫ Much greater than (relation). Similar: much less than \ll.

ℏ Planck constant over two pi (ordinary).

♡ Heart card suit (ordinary).

↩ Hooked left arrow (relation).

↪ Hooked right arrow (relation).

⟷ If and only if (relation). It is \Longleftrightarrow with a \thickmuskip on either side.

ℑ Imaginary part (ordinary). See: real part \Re.

Dotless i; used when you are putting an accent on an i (see Math accents).

∈ Set element (relation). See also: lowercase lunate epsilon \epsilonϵ and small letter script epsilon \varepsilon.

∞ Infinity (ordinary).

∫ Integral (operator).

ι Lowercase Greek letter (ordinary).

⨝ Condensed bowtie symbol (relation). Not available in Plain TeX.

Dotless j; used when you are putting an accent on a j (see Math accents).

κ Lowercase Greek letter (ordinary).

Λ uppercase Greek letter (ordinary).

λ Lowercase Greek letter (ordinary).

∧ Logical and (binary). Synonym: \wedge. See also logical or \lor.

⟨ Left angle, or sequence, bracket (opening). Similar: less-than <. Matches \rangle.

{ Left curly brace (opening). Synonym: \{. Matches \rbrace.

[ Left square bracket (opening). Synonym: [. Matches \rbrack.

⌈ Left ceiling bracket, like a square bracket but with the bottom shaved off (opening). Matches \rceil.

≤ Less than or equal to (relation). This is a synonym for \leq.

⇝ Squiggly right arrow (relation). To get this symbol outside of math mode you can put \newcommand*{\Leadsto}{\ensuremath{\leadsto}} in the preamble and then use \Leadsto instead.

⇐ Is implied by, double-line left arrow (relation). Similar: single-line left arrow \leftarrow.

← Single-line left arrow (relation). Synonym: \gets. Similar: double-line left arrow \Leftarrow.

↽ Single-line left harpoon, barb under bar (relation).

↼ Single-line left harpoon, barb over bar (relation).

⇔ Bi-implication; double-line double-headed arrow (relation). Similar: single-line double headed arrow \leftrightarrow.

↔ Single-line double-headed arrow (relation). Similar: double-line double headed arrow \Leftrightarrow.

≤ Less than or equal to (relation). This is a synonym for \le.

⌊ Left floor bracket (opening). Matches: \floor.

◁ Arrowhead, that is, triangle, pointing left (binary). For the normal subgroup symbol you should load amssymb and use \vartriangleleft (which is a relation and so gives better spacing).

≪ Much less than (relation). Similar: much greater than \gg.

¬ Logical negation (ordinary). Synonym: \neg.

⟵ Long single-line left arrow (relation). Similar: long double-line left arrow \Longleftarrow.

⟷ Long single-line double-headed arrow (relation). Similar: long double-line double-headed arrow \Longleftrightarrow.

⟼ Long single-line left arrow starting with vertical bar (relation). Similar: shorter version \mapsto.

⟶ Long single-line right arrow (relation). Similar: long double-line right arrow \Longrightarrow.

∨ Logical or (binary). Synonym: \vee. See also logical and \land.

↦ Single-line left arrow starting with vertical bar (relation). Similar: longer version \longmapsto.

℧ Conductance, half-circle rotated capital omega (ordinary).

∣ Single-line vertical bar (relation). A typical use of \mid is for a set \{\, x \mid x\geq 5 \,\}.

Similar: \vert and | produce the same single-line vertical bar symbol but without any spacing (they fall in class ordinary) and you should not use them as relations but instead only as ordinals, i.e., footnote symbols. For absolute value, see the entry for \vert and for norm see the entry for \Vert.

⊨ Entails, or satisfies; double turnstile, short double dash (relation). Similar: long double dash \vDash.

∓ Minus or plus (relation).

μ Lowercase Greek letter (ordinary).

∇ Hamilton’s del, or differential, operator (ordinary).

♮ Musical natural notation (ordinary).

≠ Not equal (relation). Synonym: \neq.

↗ North-east arrow (relation).

¬ Logical negation (ordinary). Synonym: \lnot. Sometimes instead used for negation: \sim.

≠ Not equal (relation). Synonym: \ne.

∋ Reflected membership epsilon; has the member (relation). Synonym: \owns. Similar: is a member of \in.

    Long solidus, or slash, used to overstrike a following operator (relation).

Many negated operators are available that don’t require \not, particularly with the amssymb package. For example, \notin is typographically preferable to \not\in.

∉ Not an element of (relation). Similar: not subset of \nsubseteq.

ν Lowercase Greek letter (ordinary).

↖ North-west arrow (relation).

⊙ Dot inside a circle (binary). Similar: variable-sized operator \bigodot.

∮ Contour integral, integral with circle in the middle (operator).

Ω uppercase Greek letter (ordinary).

ω Lowercase Greek letter (ordinary).

⊖ Minus sign, or dash, inside a circle (binary).

⊕ Plus sign inside a circle (binary). Similar: variable-sized operator \bigoplus.

⊘ Solidus, or slash, inside a circle (binary).

⊗ Times sign, or cross, inside a circle (binary). Similar: variable-sized operator \bigotimes.

∋ Reflected membership epsilon; has the member (relation). Synonym: \ni. Similar: is a member of \in.

∥ Parallel (relation). Synonym: \|.

∂ Partial differential (ordinary).

⟂ Perpendicular (relation). Similar: \bot uses the same glyph but the spacing is different because it is in the class ordinary.

Φ Uppercase Greek letter (ordinary).

ϕ Lowercase Greek letter (ordinary). The variant form is \varphi φ.

Π uppercase Greek letter (ordinary).

π Lowercase Greek letter (ordinary). The variant form is \varpi ϖ.

± Plus or minus (binary).

≺ Precedes (relation). Similar: less than <.

⪯ Precedes or equals (relation). Similar: less than or equals \leq.

′ Prime, or minute in a time expression (ordinary). Typically used as a superscript: $f^\prime$; $f^\prime$ and $f'$ produce the same result. An advantage of the second is that $f'''$ produces the desired symbol, that is, the same result as $f^{\prime\prime\prime}$, but uses rather less typing. You can only use \prime in math mode. Using the right single quote ' in text mode produces a different character (apostrophe).

∏ Product (operator).

∝ Is proportional to (relation)

Ψ uppercase Greek letter (ordinary).

ψ Lowercase Greek letter (ordinary).

⟩ Right angle, or sequence, bracket (closing). Similar: greater than >. Matches:\langle.

} Right curly brace (closing). Synonym: \}. Matches \lbrace.

] Right square bracket (closing). Synonym: ]. Matches \lbrack.

⌉ Right ceiling bracket (closing). Matches \lceil.

ℜ Real part, real numbers, cursive capital R (ordinary). Related: double-line, or blackboard bold, R \mathbb{R}; to access this, load the amsfonts package.

↾ Restriction of a function (relation). Synonym: \upharpoonright. Not available in plain TeX. In LaTeX you need to load the amssymb package.

⦰ Reversed empty set symbol (ordinary). Related: \varnothing. Not available in plain TeX. In LaTeX you need to load the stix package.

⌋ Right floor bracket, a right square bracket with the top cut off (closing). Matches \lfloor.

◁ Arrowhead, that is, triangle, pointing right (binary). For the normal subgroup symbol you should instead load amssymb and use \vartriangleright (which is a relation and so gives better spacing).

ρ Lowercase Greek letter (ordinary). The variant form is \varrho ϱ.

⇒ Implies, right-pointing double line arrow (relation). Similar: right single-line arrow \rightarrow.

→ Right-pointing single line arrow (relation). Synonym: \to. Similar: right double line arrow \Rightarrow.

⇁ Right-pointing harpoon with barb below the line (relation).

⇀ Right-pointing harpoon with barb above the line (relation).

⇌ Right harpoon up above left harpoon down (relation).

↘ Arrow pointing southeast (relation).

⧵ Set difference, reverse solidus or reverse slash, like \ (binary). Similar: backslash \backslash and also \textbackslash outside of math mode.

♯ Musical sharp (ordinary).

Σ uppercase Greek letter (ordinary).

σ Lowercase Greek letter (ordinary). The variant form is \varsigma ς.

∼ Similar, in a relation (relation).

≃ Similar or equal to, in a relation (relation).

∫ Integral sign that does not change to a larger size in a display (operator).

⌣ Upward curving arc, smile (ordinary).

♠ Spade card suit (ordinary).

⊓ Square intersection symbol (binary). Similar: intersection cap.

⊔ Square union symbol (binary). Similar: union cup. Related: variable-sized operator \bigsqcup.

⊏ Square subset symbol (relation). Similar: subset \subset. Not available in plain TeX. In LaTeX you need to load the amssymb package.

⊑ Square subset or equal symbol (binary). Similar: subset or equal to \subseteq.

⊐ Square superset symbol (relation). Similar: superset \supset. Not available in plain TeX. In LaTeX you need to load the amssymb package.

⊒ Square superset or equal symbol (binary). Similar: superset or equal \supseteq.

⋆ Five-pointed star, sometimes used as a general binary operation but sometimes reserved for cross-correlation (binary). Similar: the synonyms asterisk * and \ast, which are six-pointed, and more often appear as a superscript or subscript, as with the Kleene star.

⊂ Subset (occasionally, is implied by) (relation).

⊆ Subset or equal to (relation).

≻ Comes after, succeeds (relation). Similar: is less than >.

⪰ Succeeds or is equal to (relation). Similar: less than or equal to \leq.

∑ Summation (operator). Similar: Greek capital sigma \Sigma.

⊃ Superset (relation).

⊇ Superset or equal to (relation).

√ Radical symbol (ordinary). The LaTeX command \sqrt{...} typesets the square root of the argument, with a bar that extends to cover the argument.

↙ Southwest-pointing arrow (relation).

τ Lowercase Greek letter (ordinary).

θ Lowercase Greek letter (ordinary). The variant form is \vartheta ϑ.

× Primary school multiplication sign (binary). See also \cdot.

→ Right-pointing single line arrow (relation). Synonym: \rightarrow.

⊤ Top, greatest element of a partially ordered set (ordinary). See also \bot.

△ Triangle (ordinary).

◁ Not-filled triangle pointing left (binary). Similar: \lhd. For the normal subgroup symbol you should load amssymb and use \vartriangleleft (which is a relation and so gives better spacing).

▷ Not-filled triangle pointing right (binary). For the normal subgroup symbol you should instead load amssymb and use \vartriangleright (which is a relation and so gives better spacing).

⊴ Left-pointing not-filled underlined arrowhead, that is, triangle, with a line under (binary). For the normal subgroup symbol load amssymb and use \vartrianglelefteq (which is a relation and so gives better spacing).

⊵ Right-pointing not-filled underlined arrowhead, that is, triangle, with a line under (binary). For the normal subgroup symbol load amssymb and use \vartrianglerighteq (which is a relation and so gives better spacing).

⇑ Double-line upward-pointing arrow (relation). Similar: single-line up-pointing arrow \uparrow.

↑ Single-line upward-pointing arrow, diverges (relation). Similar: double-line up-pointing arrow \Uparrow.

⇕ Double-line upward-and-downward-pointing arrow (relation). Similar: single-line upward-and-downward-pointing arrow \updownarrow.

↕ Single-line upward-and-downward-pointing arrow (relation). Similar: double-line upward-and-downward-pointing arrow \Updownarrow.

↾ Up harpoon, with barb on right side (relation). Synonym: \restriction. Not available in plain TeX. In LaTeX you need to load the amssymb package.

⊎ Multiset union, a union symbol with a plus symbol in the middle (binary). Similar: union \cup. Related: variable-sized operator \biguplus.

Υ uppercase Greek letter (ordinary).

υ Lowercase Greek letter (ordinary).

ε Small letter script epsilon (ordinary). This is more widely used in mathematics than the non-variant lunate epsilon form \epsilon ϵ. Related: set membership \in.

∅ Empty set symbol. Similar: \emptyset. Related: \revemptyset. Not available in plain TeX. In LaTeX you need to load the amssymb package.

φ Variant on the lowercase Greek letter (ordinary). The non-variant form is \phi ϕ.

ϖ Variant on the lowercase Greek letter (ordinary). The non-variant form is \pi π.

ϱ Variant on the lowercase Greek letter (ordinary). The non-variant form is \rho ρ.

ς Variant on the lowercase Greek letter (ordinary). The non-variant form is \sigma σ.

ϑ Variant on the lowercase Greek letter (ordinary). The non-variant form is \theta θ.

⊢ Provable; turnstile, vertical and a dash (relation). Similar: turnstile rotated a half-circle \dashv.

∨ Logical or; a downwards v shape (binary). Related: logical and \wedge. Similar: variable-sized operator \bigvee.

‖ Vertical double bar (ordinary). See Delimiters, for how to use the mathtools package to create flexibly-sized norm symbols.

| Single line vertical bar (ordinary). For “such that” as in the definition of a set, use \mid because it is a relation. See Delimiters, for how to use the mathtools package to create flexibly-sized absolute-value symbols.

∧ Logical and (binary). Synonym: \land. See also logical or \vee. Similar: variable-sized operator \bigwedge.

℘ Weierstrass p (ordinary).

≀ Wreath product (binary).

Ξ uppercase Greek letter (ordinary).

ξ Lowercase Greek letter (ordinary).

ζ Lowercase Greek letter (ordinary).