Anaptyxis of a vowel is its insertion in the interior of a phonological word, generally between two consonants.

Example: Engl. ['æthəli:t] "athlete", [pə'tolemi:] "Ptolemy".

Insertion of a vowel is anaptyxis; insertion of a consonant is epenthesis. However, sometimes the term 'anaptyxis' is not used, and 'epenthesis' is used for both kinds of insertion. The vowel inserted is called svarabhakti.

Anaptyxis alternates with syncope in the same context.