Riley is a transferred use of an English surname derived from Old English ryge 'rye' + lēah 'wood, clearing'.
[1][2] It is also derived from the Irish surname O'Reilly,[3] which originated from the Irish name Raghallach, of unknown meaning.
[5] Until the 1990s and early 2000s, Riley was primarily a boy's name in the United States.
However, it has become a popular name for girls in the United States and remains in wide use there for girls, with many variant spellings also in use, including Reiley, Reilly, Reily, Rhilee, Rhiley, Rhylee, Rhylei, Rhyleigh, Rhyley, Rhyli, Rhylie, Rielee, Rilee, Rileigh, Rilie, Ryelee, Rylea, Rylee, Rylei, Ryleigh, Ryley, Ryli, Rylie, Ryliee, and Ryliegh.
It also remains a well-used name there for boys, also with variant spellings.