The word "infixation" refers to the act of adding an affix to the middle of a word, such as the "in-" in "infixation." There are several synonyms for this word including "intercalation," "interposition," "interjection," "insertion," and "injection." Each of these words refers to the insertion of something between two other things, whether it be a letter in a word or an object in a space. While these words are similar in meaning, they may be used in different contexts depending on the situation. Regardless of which word is used, they all describe the act of inserting something into the middle of something else.