DIDYMUS.—The alternative name of the Apostle Thomas, given in three passages in the Fourth Gospel (John 11:15; John 20:24; John 21:2 Θωμᾶς ὁ λεγόμενος Δίδυμος). The adj. δίδυμος is regular Greek from Homer onwards, with the meaning ‘twofold’; hence δίδυμος as subs. = ‘a twin.’ Δίδυμος is the translation, as Θωμᾶς is the transliteration, of תִּאם = תֹּאמָא ‘a twin.’
Why St. John calls special attention to this name is not clear. Westcott suggests that Thomas may have been familiarly known in Asia Minor among the Gentile Christians as Didymus. John 4:25 (‘Messiah … which is called Christ’) shows that Thomas was not called Didymus as an additional name. See Thomas.
E. H. Titchmarsh.