Most protrusive is defined as the quality of sticking out or extending beyond something. The antonyms for this word would be words that describe something that is recessed, indented, or sunk below a surface. Examples of antonyms for most protrusive include words like sunken, concave, hollow, depressed, dented, or indented. These words describe objects that have a lower profile or are set back from a surface. For instance, a sinkhole is a depression or concave feature in the ground. Similarly, an indented surface is set back or depressed below the surrounding surface. In essence, these antonyms are used to describe objects that are opposite in nature to something that sticks out or projects beyond a surface.