The crossword solutions for the term 'WAS A TRIBUTARY OF' are 'FED' (3 letters) and 'FEDINTO' (7 letters). A tributary is a stream or river that flows into a larger body of water, such as a lake or ocean. Therefore, the phrase 'WAS A TRIBUTARY OF' implies that something was once a tributary of another body of water. In this case, the answer is 'FED' and 'FEDINTO', which suggests that something was once a tributary of a river or stream called 'FED' that fed into another body of water.