As a noun, a simian is a monkey or ape. Something monkey- or ape-like can be described using the adjective simian. So: something can be simian without being a simian. Got it?
The first syllable in simian rhymes with dim and gets the accent: "SIM-ee-an." This is a case in which the adjective form came before the noun. How? Simian comes from the Greek word simos, meaning "snub-nosed, bent upward." It wasn't until the late nineteenth century that this description became the label for those animals whose noses simian describes.