Thoams in Easton's Bible Dictionary

twin, one of the twelve (Matt. 10:3; Mark 3:18, etc.). He was also called Didymus (John 11:16; 20:24), which is the Greek equivalent of the Hebrew name. All we know regarding him is recorded in the fourth Gospel (John 11:15, 16; 14:4, 5; 20:24, 25, 26-29). From the circumstance that in the lists of the apostles he is always mentioned along with Matthew, who was the son of Alphaeus (Mark 3:18), and that these two are always followed by James, who was also the son of Alphaeus, it has been supposed that these three, Matthew, Thomas, and James, were brothers.