Sheelagh is a variant of the name Sheila, which itself is an anglicized form of the Irish name Síle, derived from the Latin name Cecilia. The name Cecilia originates from the Roman family name Caecilius, which is believed to be derived from the Latin word 'caecus,' meaning 'blind.' Sheelagh, like Sheila, has been used primarily in English-speaking countries and carries connotations of purity and light, often associated with the Christian martyr Saint Cecilia.