* Contractions: This is the most common use of apostrophes to combine words by shortening them and replacing omitted letters with an apostrophe. Examples: "don't" (do not), "can't" (cannot), "it's" (it is).
* Possessives: Apostrophes are used to show ownership or possession. Examples: "the dog's bone", "Sarah's book", "the children's toys".
Therefore, the specific term depends on the context of combining words with apostrophes. It's either contraction or possessive.
If you have a specific example in mind, I might be able to give you a more precise answer.