Read the dictionary definition of realm. All definitions for this word.
1. a knowledge domain that you are interested in or are communicating about
1. it was a limited realm of discourse
2. here we enter the region of opinion
3. the realm of the occult
2. the domain ruled by a king or queen
3. a domain in which something is dominant
1. the untroubled kingdom of reason
2. a land of make-believe
3. the rise of the realm of cotton in the south