infixes

Infixes are a type of bound morpheme that is inserted inside a word, rather than at its beginning or end. They differ from prefixes and suffixes in that their position is internal, often after the initial consonant or syllable of a stem. Infixation is found in a variety of languages, though it is especially well documented in Austronesian languages such as Tagalog.

Infixes can carry grammatical or derivational meaning, including aspects of tense, voice, mood, or aspect, and they sometimes affect the word’s class or meaning. Different languages use different infixes, and some may employ more than one productive infix in a single system. The placement of an infix is typically constrained by the phonology and structure of the language.

Tagalog provides well-known examples. The infix -um- is inserted after the first consonant of a root to form new verb forms, as in sulat “to write” becoming sumulat, and tawa “to laugh” becoming tumawa. The infix -in- is used in other derivations to express completed action or different voice, as in bili “to buy” becoming binili “was bought.” These patterns illustrate how infixes operate inside the stem to produce related forms without attaching to the word edge.

Not all languages have productive infixes; many rely primarily on prefixes and suffixes. When infixation occurs, it often interacts with the language’s syllable structure and phonology, shaping which forms are permissible. Infixes are thus a key example of the diversity of word-formation strategies across languages. See also: affix, infixation, Austronesian linguistics.