epentesis

Epentesis, also known as epenthesis, is a phonological process in which an extra sound is inserted within a word. The inserted segment is usually a vowel, but it can also be a consonant. The purpose of epentesis is to facilitate pronunciation, adjust a word to a language’s syllable structure, or resolve difficult consonant combinations. When the inserted material is a vowel, the term most often used is vowel epenthesis; when a consonant is added, it is called consonant epenthesis.

Vowel epenthesis involves inserting a vowel to break up a cluster of consonants or to bridge a hiatus between syllables. The inserted vowel is frequently a neutral or mid vowel such as schwa [ə], but the exact vowel can vary by language and context. Consonant epenthesis, by contrast, adds a consonant to the word and can serve to flesh out syllables or avoid certain phonotactic sequences. Commonly inserted consonants include glides like [j] or [w], or a simple stop in some languages.

Epentesis occurs in many languages and in multiple domains. It can be productive in loanword adaptation, where a language reshapes a foreign term to fit its phonotactics, or it can arise in dialectal variation and historical sound change. It also functions to mark boundaries between morphemes or to ease articulation in rapid speech.

Illustrative examples include the adaptation of foreign terms into Japanese, where vowels are inserted to fit a CV syllable structure (for example, space becomes supēsu, and baseball becomes beisbōru). Such instances showcase how epentesis interacts with phonology, morphology, and cross-linguistic contact.