Learner's definition of REALM
1 : an area of activity, interest, or knowledge
new discoveries in the realm of medicine
in political and legal realms
the realm of art/science/education
A victory by the team seems within the realm of possibility. [=a victory seems possible]
It's not beyond the realm of possibility [=it's not impossible] that he will return.
2 : a country that is ruled by a king or queen