# inclusion

> English word · Noun · IPA /ɪnˈkluːʒən/ · frequency rank #6,921

## Definitions
1. An addition or annex to a group, set, or total.
2. The act of including, i.e. adding or annexing, (something) to a group, set, or total.
3. Anything foreign that is included in a material.
4. Any material that is trapped inside a mineral during its formation, as a defect in a precious stone.
5. A nuclear or cytoplasmic aggregate of stainable substances.
6. An object completely inside a tissue, such as epidermal inclusion cyst, a cyst in the epidermis.
7. A mapping where the domain is a subset of the image.
8. Restriction; limitation.

## Etymology
Borrowed from Latin inclusio, inclusionis, from the verb Latin inclūdō (“to shut in, enclose, insert”), from in- (“in”) + claudō (“to shut”), ultimately from Proto-Indo-European *kleh₂u- (“key, hook, nail”). By surface analysis, include + -sion. Doublet of enclosure.

## Easily confused with
- **infusion** (https://plainspell.com/en/vs/inclusion-vs-infusion)
- **inclusive** (https://plainspell.com/en/vs/inclusion-vs-inclusive)
- **intrusion** (https://plainspell.com/en/vs/inclusion-vs-intrusion)
- **incursion** (https://plainspell.com/en/vs/inclusion-vs-incursion)
- **illusion** (https://plainspell.com/en/vs/illusion-vs-inclusion)
- **incision** (https://plainspell.com/en/vs/incision-vs-inclusion)

## Common misspellings (14)
`icnlusion`, `incclusion`, `incllusion`, `inclsuion`, `incluison`, `inclusino`, `inclusionn`, `inclusoin`, `inclussion`, `inclution`, `inculsion`, `inlcusion`, `innclusion`, `niclusion`

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/inclusion