Suffixes

Suffixes are morphemes attached to the end of a word or its base to modify its meaning or grammatical function. They are a type of affix, contrasted with prefixes that attach to the beginning and infixes that insert inside a word. In many languages, suffixes can signal tense, number, case, mood, or person, as well as derive new words or change their part of speech.

English inflectional suffixes include -s for plural (cats), -ed for past tense (walked), -ing for present participle (walking). Derivational suffixes include -ness to form nouns (happiness), -ful to form adjectives (careful), -ment to form nouns (development), -er to denote agent (teacher), -ize to form verbs (publicize).

Some languages rely heavily on suffixation; German uses -en, -e, -er to form nouns and verbs; Turkish uses extensive suffix chains to indicate case, possession, and plurality; Finnish is highly agglutinative with numerous suffixes.

Suffix placement allows stacking and complex word formation, but suffix order can be fixed; misplacement can produce ungrammatical forms.

In computing, a suffix may refer to a file extension, the letters after a period that indicate file type, such as .txt, .pdf, or .jpg. This use is distinct from linguistic suffixes but shares the idea of a trailing marker.

Historically, suffixes are among the oldest morphological tools and recur across languages, often deriving from older words and affixes that joined to form new forms.

See also infix, circumfix, agglutination.