There are various synonyms for the word "surface" that can be useful in expanding one's vocabulary. Some of these synonyms include exterior, top, skin, crust, facade, and veneer. These words represent the outermost layer or layer(s) of an object or material. Other synonyms for surface include level, plane, and even. These words describe a flat and smooth area. Moreover, "surface" can also be expressed as the word "face" which is often used in mathematical terms, such as the faces of a cube. Using synonyms like these can help to provide clarity and variety in writing and communication.