There are several synonyms for the word "interjected." One alternative is "interrupted," which communicates a break in the conversation or flow of ideas. Another similar option is "inserted," which implies adding a comment or thought into the conversation. "Injected" is another word that can be used to indicate the forceful introduction of an idea or opinion into the discussion. A more formal synonym is "interposed," which suggests placing oneself between two parties or ideas to mediate or clarify. Finally, "butted in" is a more colloquial slang term that connotes an abrupt and unwelcome interruption.