arena vs kingdom

arena and kingdom both are nouns.

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

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

arena (noun)	kingdom (noun)
a playing field where sports events take place	a basic group of natural objects
a large structure for open-air sports or entertainments	a monarchy with a king or queen as head of state
the central area of an ancient Roman amphitheater where contests and spectacles were held; especially an area that was strewn with sand	the highest taxonomic group into which organisms are grouped; one of five biological categories: Monera or Protoctista or Plantae or Fungi or Animalia
a particular environment or walk of life	the domain ruled by a king or queen
	a country with a king as head of state
	a domain in which something is dominant