There are many antonyms for the word "omphaloses," which refers to the protrusion of the navel. Some potential antonyms could include "inward," "flat," "recessed," "sunken," or "concave." These words all imply a lack of protrusion or outward movement, which is the opposite of omphaloses. It's important to note that antonyms can vary widely depending on the context and the specific meaning of the word in question. In some cases, antonyms may be exact opposites, while in other cases they may be related concepts that have a different meaning. Therefore, when looking for antonyms, it's important to consider the broader context and meaning of the word being used.