Infixes

An infix is an affix inserted inside a word stem (an existing word or the core of a family of words). It contrasts with adfix, a rare term for an affix attached to the outside of a stem, such as a prefix or suffix.

Tmesis is either the dividing of a word into two parts, with another word inserted between those parts, thus forming a compound word, or, in a broader sense, a set phrase, such as a phrasal verb, with one or more words interpolated within, thus creating a separate phrase.