cercus

As an adjective cerous

is (chemistry) containing cerium with valence three.

As a noun cercus is

certain hair-like sensory structures on some types of insects.

As nouns the difference between cercus and circus

is that cercus is certain hair-like sensory structures on some types of insects while circus is a traveling company of performers that may include acrobats, clowns, trained animals, and other novelty acts, that gives shows usually in a circular tent.

As a proper noun cereus

is .

As a noun cercus is

certain hair-like sensory structures on some types of insects.