🔍

Loading symbols…

››

∖

set minus

Set minus

∖ means “keep what belongs to the first set and leave out anything also in the second.” In A ∖ B, only A’s members that are not in B remain. Some books use an ordinary minus sign for the same operation, so context distinguishes set notation from arithmetic.

Text symbol

Also called: set difference · set subtraction
Search it as: setminus · relative complement · exclude from a set
Shows up in: Anything that takes text · its shape is whatever your font draws

What ∖ means

Set difference keeps elements in the first set, not the second.

A set is a collection of items: in A ∖ B, start with A and remove every item that also belongs to B. The result is another set, not a number, and reversing A and B can change it.

Set theory developed a broader symbol vocabulary over time. Giuseppe Peano in 1888 used ∪ and ∩ for union (combining sets) and intersection (their shared elements).

Mathematical and technical; use it between set expressions when the surrounding notation makes that reading clear.

A ∖ B and B ∖ A need not match; the first set is the one you keep from.

What it means when someone sends it to you

2 readings

A ∖ B in a definition

The elements in A that are not in B.

U ∖ A with universe U

Everything in U outside A; this is A’s complement within that universe.

Don't confuse it with

Reverse Solidus

The diagonal stroke can look like a plain backslash, which is used in computing and other notation. Between sets, ∖ marks set difference.

−

Minus Sign

Some books use the ordinary minus sign for this set operation; in arithmetic, it subtracts numbers.

Questions people ask

Why does ∖ show as a box on some devices?

Because that device's fonts have no glyph for it. The character is still correct and still copies correctly — the box is a missing glyph, not a broken character.

How to type ∖

Windows (Word)

Alt+XType 2216, then Alt+X to get ∖.

Windows

Win+Rrun charmap for the full table, or use the emoji picker's Ω symbols tab (Win + .).

macOS

Control+Command+SpaceOpen the character viewer and search “set minus”.

Linux

Ctrl+Shift+UType 2216, then Enter or Space.

HTML

∖

CSS

\2216

Linux (GNOME/GTK)

As of 2026, in GNOME/GTK fields press Ctrl+Shift+U, type 2216, then press Space or Enter.

Windows (Word)

As of 2026, in Microsoft Word type 2216, then press Alt+X. This is app-specific, not a Windows-wide shortcut.

Codes and encoding1 code points

HTML decimal

∖

HTML hex

∖

CSS content

content: "\2216";

Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.

URL encoded

%E2%88%96

On screen

Code points

JS .length

UTF-8 bytes

A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.

Families this belongs to

Maths & numbers1,835 symbols

1️⃣📏📐✖️➕➖➗🟰♾️#️⃣*️⃣0️⃣