The term "most corneous" refers to something that is extremely horny or tough. Synonyms for this word include "hardened," "callused," "stiffened," "thickened," "hornlike," and "rigid." These words reflect the strong and unyielding nature of something that is most corneous. Other synonyms that can be used in this context include "crusty," "coarse," and "rough." These words suggest an outer layer that is both rough and tough, which is typical of things that are most corneous. By using these synonyms, one can describe the texture and strength of something in a more precise and descriptive manner.