When talking about becoming narrower, there are a variety of synonyms that can be used to help emphasize the gradual reduction in size or space. Some common synonyms for "become narrower" include to constrict, to shrink, to taper, to diminish, to decrease, to tighten, to compress, to narrow down, to slim down, to slim, to pare down, to reduce, to truncate and to downsize. Choosing the right synonym can help to enhance the meaning of a statement and make it clearer to the reader. It's important to choose the appropriate word to accurately convey the intended meaning and emphasize the right message.