The term 'be subject to fluctuation' can be summarized using the crossword solutions of noun (4 letters) and labile (6 letters). A noun is a part of speech that refers to a person, place, thing, or idea. Labile is an adjective that describes something that is easily changed or affected by external factors. Therefore, the term 'be subject to fluctuation' can be summarized as something that is easily changed or affected by external factors.