- Derived from the name of the old Irish clan Ó Raghallaigh
- Means a friendly people/sociable race, from the compound name Raghallach (ragh meaning “race,” and ceallach meaning “sociable”)
- Commonly used as a unisex given name and as a last name
- Variants include Riley, Ryley and Rylee
- As a surname, common in another form: O’Reilly