Fit refers to a state of being in good physical condition or to describe something that is the correct size or shape. There are many synonyms to the word fit such as healthy, vigorous, agile, trim, muscular, toned, and robust, which all describe a state of being well and physically capable. Fit can also describe something that is proper or appropriate like suitable, compatible, fitting, appropriate, and acceptable. It can also refer to something that is able to function or operate correctly or easily, like functioning, able, capable, adapted, and efficient. Overall, there are many words that can replace fit depending on the context and meaning of the sentence.