Ayr.
Depending on your pronunciation, you could use "air" or "hair"
the homophone for heir is air
The word "ayre" is pronounced as "air." It rhymes with "bear" and "care." This pronunciation is consistent across various contexts in which the term might be used.
heir/air (NOT hair!)
The homophone for heir is air.
The homophone of "heir" is "air."
heir/air (NOT hair!)
air, ere, err
The homophone for "heir" is "air."
Heir - She is the heir to the throne.
air, ere, err
The royal heir had an air of entitlement about him.