Riley

The Irish surname Raghallaigh — pronounced roughly RYE-lee in modern Irish, anglicized into Riley, Reilly, and O'Reilly across centuries of emigration — belonged to a clan from County Cavan in the medieval kingdom of Bréifne, with a recorded ancestry stretching back to the tenth century. The clan's modern descendants are spread widely across Ireland and the Irish-American diaspora. Somewhere in the late nineteenth or early twentieth century the surname picked up the English idiom "the life of Riley" (origin uncertain, possibly from a 1880s Pat Rooney vaudeville song or from the comic strip and radio show of the same name), meaning a life of ease, good humor, and idle prosperity.

The name crossed from Irish-American surnames into first-name use in the late twentieth century, and from boys' column to girls' and back, until it simply lived comfortably in both. It now sits at rank forty-two in the United States, ranked higher for girls than boys but used widely for both. The 2015 Pixar film Inside Out, with its eleven-year-old protagonist Riley Andersen, gave the name another lift.

Famous Rileys include Riley Keough (Lisa Marie Presley's daughter, the actress), Riley Reid, the country singer Riley Green, and Riley B. King — better known as B.B. King. Two bouncy syllables, all vowels and a soft L — RYE-lee — pronounced exactly as spelled. Pairs cleanly with both unisex and gender-leaning middles (Riley Mae, Riley June, Riley Cruz, Riley Wren). Nicknames are scarce; the name is already short. Preppy, modern, unambiguously cheerful — the kind of name you'd expect to answer to with a grin.