Genesis 25:24 - Clarke's commentary and critical notes on the Bible

And when her days to be delivered were fulfilled, behold, there were twins in her womb. There were twins - תומם thomim, from which comes Thomas, properly interpreted by the word Διδυμος, Didymus, which signifies a twin; so the first person who was called Thomas or Didymus, we may take for granted, had this name from the circumstance of his being a twin.