An affix is a morpheme that is attached to a base morpheme to form a word. An affix can be a prefix (something attached at the front), a suffix (attached at the back), an infix (in between) or a circumfix (two parts, one in front, the other at the back). Affixes are Bound morphemes by definition. Affixes are essential in agglutination.

Example:

• establish (verb) + -ment (suffix) --> establishment (noun).

See also

• affixation
• derivation
• list of English prefixes
• list of English suffixes