heir apparent
person who is first in line of succession and cannot be displaced from inheriting, except by death or a change in the rules of succession
en-GB/ˈɛə əˈpæɹənt/
en-US/ˈɛɹ əˈpɛɹənt/
person who is first in line of succession and cannot be displaced from inheriting, except by death or a change in the rules of succession