Postfixes

Postfixes are bound morphemes that attach to the end of a word or stem. The term emphasizes their position after the base form, in contrast to prefixes, which attach at the beginning, or infixes, which insert inside the word. In linguistic practice, postfixes function similarly to suffixes, but the label highlights the post-root location.

Postfixes serve derivational or inflectional functions. Derivational postfixes create new words or alter word class (for example, forming a noun from an adjective), while inflectional postfixes mark grammatical categories such as tense, aspect, voice, number, case, or mood. Multiple postfixes can accumulate on a single stem, and their order is constrained by phonology and morphology.

Examples from English illustrate common postfixes: -ed marks past tense (talk → talked); -ing forms the present participle (run → running); -s or -es marks plural or third-person singular (cat → cats; box → boxes); -ness forms a noun from an adjective (happy → happiness); -ship derives a noun (friend → friendship). In other languages, postfixation can be more extensive. Turkish, Finnish, and other agglutinative languages often attach long sequences of postfixes to convey tense, mood, number, possession, case, and other grammatical relations in a single word.

Postfixes are a key feature in many morphological systems and are central to the study of word formation and syntax in languages that rely on suffixal or post-root morphology. They contrast with prefixes in position and with infixes in internal attachment, and they interact with phonological and syntactic constraints to shape word structure.