An heir apparent is the person certain to inherit a title. The heir apparent, named as heir apparent, the heir apparent to the throne.
It differs from an heir presumptive, whose claim can be displaced by a later birth, which is a real distinction in royal succession. The adjective follows the noun because the phrase was translated whole from French.
1nounheir apparentThe person certain to inherit a title.
“As the king's eldest son, he was the heir apparent to the throne.”
heir apparent is a successor.
A calque of Middle French heritier apparent, which is why the adjective follows the noun.
Middle French
héritier apparent
Middle English
heier apparaunt
English, today
heir apparent
From Middle English heier apparaunt, a calque translation of Middle French héritier apparent, hence the unusual order of adjective following noun.
Etymology from Wiktionary, CC BY-SA
Practised in History & Eras