Princeton's WordNet

1. Thomas, Saint Thomas, St. Thomas, doubting Thomas, Thomas the doubting Apostle(noun)

   the Apostle who would not believe the resurrection of Jesus until he saw Jesus with his own eyes

2. Aquinas, Thomas Aquinas, Saint Thomas, St. Thomas, Saint Thomas Aquinas, St. Thomas Aquinas(noun)

   (Roman Catholic Church) Italian theologian and Doctor of the Church who is remembered for his attempt to reconcile faith and reason in a comprehensive theology; presented philosophical proofs of the existence of God (1225-1274)