The term "fill-ins" can have multiple synonyms depending on the context in which it is being used. In the context of crossword puzzles or trivia games, fill-ins can be referred to as "clues" or "hints" that assist in finding the correct answer. Another synonym for fill-ins is "placeholders," which are used in the absence of something that will later be filled in completely. In the case of missing information, fill-ins can be referred to as "substitutes" or "alternatives," while in the context of musicians, they may be called "session players" or "back-up musicians." Regardless of the specific synonym used, fill-ins serve a crucial role in various settings, making tasks easier and more efficient for individuals.