The Collaborative International Dictionary of English v.0.48:

Seth \Seth\, prop. n. (Egyptian Mythology)
   An evil beast-headed god with high square ears and a long
   snout; his was the brother and murderer of Osiris. Called
   also Set
   [WordNet 1.6]

The Collaborative International Dictionary of English v.0.48:

Set \Set\, prop. n. (Egyptian Mythology)
   An evil beast-headed god with high square ears and a long
   snout; his was the brother and murderer of Osiris. Called
   also Seth
   [WordNet 1.6]

WordNet (r) 3.0 (2006):

Seth
    n 1: (Old Testament) third son of Adam and Eve; given by God in
         place of the murdered Abel
    2: evil Egyptian god with the head of a beast that has high
       square ears and a long snout; brother and murderer of Osiris
       [syn: Set, Seth]