circus vs arena

circus and arena both are nouns.

Word	Noun	Adjective	Verb	Adverb
circus	Yes	No	No	No
arena	Yes	No	No	No

As nouns, arena is a hypernym of circus; that is, arena is a word with a broader meaning than circus:

circus: an arena consisting of an oval or circular area enclosed by tiers of seats and usually covered by a tent
arena: a playing field where sports events take place

Other hypernyms of circus include scene of action.

As nouns, arena is a hypernym of circus; that is, arena is a word with a broader meaning than circus:

circus: (antiquity) an open-air stadium for chariot races and gladiatorial games
arena: a large structure for open-air sports or entertainments

Other hypernyms of circus include bowl, sports stadium, stadium.

circus (noun)	arena (noun)
a performance given by a traveling company of acrobats, clowns, and trained animals	a playing field where sports events take place
a frenetic disorganized (and often comic) disturbance suggestive of a large public entertainment	a large structure for open-air sports or entertainments
an arena consisting of an oval or circular area enclosed by tiers of seats and usually covered by a tent	the central area of an ancient Roman amphitheater where contests and spectacles were held; especially an area that was strewn with sand
(antiquity) an open-air stadium for chariot races and gladiatorial games	a particular environment or walk of life
a travelling company of entertainers; including trained animals