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Wiktionary
interfix

n. 1 (context morphology English) An empty morph inserted between two morphemes in the process of word formation, such as English (term -o- English), (term -i- English). 2 (context computing information retrieval dated English) An association link, a device to group multiple words or concepts. vb. 1 (context engineering English) To attach or anchor two or more parts together. 2 (context morphology English) To insert an interfix between two morphemes.

Wikipedia
Interfix

Interfix, or, more commonly, linking element, is a term in linguistics and more specifically, phonology. It describes a phoneme which is placed in between two morphemes and does not have a semantic meaning.