Barnabas, Saint, Christian apostle. He was a Cypriot and a relative of St. Mark; his forename was Joseph. Several passages in the New Testament relate that Barnabas was a teacher and prophet in the church at Antioch and the companion of St. Paul on his first missionary journey. He is said to have been martyred in Cyprus. One of the oldest noncanonical Christian writings (about 2d cent. A.D.) is a letter attributed to Barnabas. Feast: June 11.