From an Irish surname which was derived from Ó Riain meaning “descendent of Rían”. The given name Rían probably means “little king” (from Irish rí “king” combined with a diminutive suffix).
Greek form of the Aramaic name תָּאוֹמָא (Ta’oma’) which meant “twin”. In the New Testament this was the name of the apostle who initially doubted the resurrected Jesus. According to tradition he was martyred in India. Due to his renown, the name came into general use in the Christian world.
In England the name was introduced by the Normans and became very popular due to Saint Thomas Becket, a 12th-century archbishop of Canterbury and martyr. Another notable saint by this name was the 13th-century Italian philosopher and theologian Thomas Aquinas, who is regarded as a Doctor of the Church. Other famous bearers include philosopher Thomas Hobbes (1588-1679), American president Thomas Jefferson (1743-1826), novelist Thomas Hardy (1840-1928), and inventor Thomas Edison (1847-1931).