Simious is an adjective that means reminiscent of or resembling a monkey or ape in appearance or behavior. Synonyms for simious can include primate-like, ape-like, monkey-like, monkeyish, baboonish, and gorilla-like. These words all convey the idea of being similar to primates in some way, whether in physical appearance or behavioral characteristics. Other synonyms for simious may include animalistic, bestial, or savage, but these terms have a more negative connotation and suggest a lack of human qualities rather than merely resembling monkeys or apes. Overall, using a synonym for simious can help to add variety to one's writing and make it more interesting to read.