The name Seamus is a boy's name of Irish origin meaning "supplanter". Seamus is ranked #977 on our popularity charts and is often added to lists like Irish Baby Names for Boys and discussed in our forums with posts like "Picky Parents BNG".
From the experts:
Parents who have tired of Sean are now contemplating Seamus, the Irish form of James, which has a lot more substance and verve.
One of the name's most famous bearers is the 1995 Nobel Prize-winning Irish poet Seamus Heaney. Seamus is also a Harry Potter name—Seamus Finnigan is a half-blood wizard friend of Harry's.
At a time when the police force was predominantly Irish, "shamus" became a slang term for a detective.