Roisin is the anglicized spelling of the Irish Róisín, "little rose", a diminutive of Róis; the old poem Róisín Dubh, known in English as Dark Rosaleen, uses the name as a symbol of Ireland itself. It is one of the most popular girls' names in Ireland but rare in the United States, where the pronunciation ro-SHEEN keeps it a connoisseur's choice. Roisin has climbed from number 4,959 in 2015 to number 2,716 in 2025, its best rank, with 64 births.