arena vs dome

arena and dome both are nouns.

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

As nouns, dome is a hyponym of arena; that is, dome is a word with a more specific, narrower meaning than arena:

arena (noun)	dome (noun)
a playing field where sports events take place	a hemispherical roof
a large structure for open-air sports or entertainments	a stadium that has a roof
the central area of an ancient Roman amphitheater where contests and spectacles were held; especially an area that was strewn with sand	informal terms for a human head
a particular environment or walk of life	a concave shape whose distinguishing characteristic is that the concavity faces downward