Inter-lineate is a verb that refers to the process of inserting lines in between existing lines. There are several synonyms for this word, which include intersperse, insert, intercalate, interject, interpose, and alternate. All these words imply the act of adding something in between or amidst a pre-existing structure. For instance, you might intercalate a new paragraph between two existing paragraphs in a text. Similarly, you may interject a thought or comment in between the lines of a conversation. These synonyms for inter-lineate are helpful when you want to inject some additional information or add variety to your writing or speech.