A shorter, Anglicized version of the Gaelic surname Mac Thighearnáin, meaning “son of Tiernan.” But Kiernan’s unisex appeal means that you can use it for a daughter too. Even if there’s not a Tiernan to be found in your entire family tree.
Famous people named Kiernan:
Actress Kiernan Shipka; rapper Kiernan Forbes (a.k.a. AKA); pianist Kiernan Box.
The McKiernans (where this name originated) were very prominent clan leaders in ancient Ireland.