Shallowing is a word that refers to the act of making something less deep or reducing its depth. Synonyms for this word include "shallowing out," "narrowing," "diluting," and "making it more shallow." Other related terms that could be used in place of shallowing include "wading," "shoaling," and "swimming in the shallows." These terms all suggest an activity that involves reducing the depth or making something more shallow. Overall, there are many different synonyms for the word shallowing, and each one can be used to convey a slightly different shade of meaning or nuance, depending on the context in which it is used.