You searched for: “infixation
infixation (s) (noun), infixations (pl)
A bound morpheme or grammatical unit that never occurs by itself, but is attached or inserted within a root or a word stem as a sound or a letter: In the term "originally" the  infixation "al" is preceded by "origin" (the root) and "ly" (indicating the adverbial form of the term).
This entry is located in the following unit: fix- (page 3)