Inumbrating is a relatively uncommon word that means "to cast a shadow upon," but there are a number of synonyms that can be used in its place. Some of these synonyms include obscuring, shading, veiling, eclipsing, darkening, dimming, and overshadowing. Depending on the context in which the word is being used, any of these synonyms might be more appropriate than inumbrating. For example, if you were describing a cloud that was blocking the sun, you might use shading or obscuring instead of inumbrating. Similarly, if you were talking about a person who was overshadowed by someone else's accomplishments, you might use eclipsing or overshadowing instead of inumbrating.