Name for similar beginnings or endings exhibited by sets of nouns / compound nouns etc (not affixes) [closed]

I remember knowing a term for "beginnings or endings" that are similar in many words. Not suffixes or prefixes.

I knew this term a long time ago but for some reason I can't recall it. I don't even remember examples but I'll try to make some up.

e.g. English Stackexchange, Biology Stackexchange, Chemistry stackexchange.

All these words have "stackexchange" ending. What is this "stackexchange" called? It's not suffix.

Another example: internet, internal, interjection, interest. All these words have "inter" in common. What's it called?

I apologize if there is the same existing question but finding it would be easy only if I knew the name and I don't know the name.

Thanks in advance.

Solution 1:

Cranberry morpheme might be what you're looking for.

Cranberry morpheme: In linguistic morphology, a cranberry morpheme (or fossilized term) is a type of bound morpheme that cannot be assigned an independent meaning or grammatical function, but nonetheless serves to distinguish one word from another.

Examples:

• Mit in permit, commit, transmit, remit, and submit, from the Latin verb mittere meaning to give, to send.
• Ceive in receive, perceive, and conceive, from the Latin verb capere meaning to seize.
• Twi in twilight.
• Cob in cobweb, from the obsolete word coppe for a spider

Many elements in English toponyms, such as -ing ("Reading," "Dorking," "Washington") from an Old English term meaning "the people of."

— Wikipedia