Reavey is an Irish surname that is derived from the Gaelic name "Ó Riabhaigh". It is a patronymic surname, which means that it is derived from the name of the father. In this case, the name "Reavey" is derived from the Gaelic name "Riabhach", which means "grey". The surname Reavey is therefore thought to have originated from a person who had grey hair or a grey beard. The name Reavey is most common in County Mayo in Ireland, but it is also found in other parts of Ireland and in other countries around the world.