The word "surfaces" is generally used to describe the outer layer of an object, area, or substance. Some common antonyms for this word include "interiors," "depths," and "undersides." These words are opposites to surfaces, as they describe what is beneath or below the surface of something. In contrast, the word "surfaces" suggests what is immediately visible or accessible. Exploring antonyms can help expand one's vocabulary, and further understanding the nuances of a particular word. Understanding the antonyms of "surfaces" can help in describing the depth, inner workings, and underside of an object or area, adding further description and detail to one's language.