Say you want to describe someone who looks like a rat or a mouse with a kind of long pointy face and prominent front teeth and twitchy disposition. “Mousy” indicates a shy person, which is not quite right, while “rat-like” has negative connotations [sorry, rats — but it’s true], and “rodent-like” is too general, given that rodents go from cabybaras to jerboas.

As a solution, I present to you the word “murine.” It means “of or pertaining to the family Muridae, a group that includes mice and rats.” It comes from the genitive plural murinus, which means “of or belonging to mice.” It also has deceptively tranquil and pleasing connotations, due to its accidental homophony with “marine.” 

Murine would make a good name for a murine therianthrope!!