Adjective
Of or pertaining to Cadmus, a fabulous prince of Thebes, who was said to have introduced into Greece the sixteen simple letters of the alphabet -- /, /, /, /, /, /, /, /, /, /, /, /, /, /, /, /. These are called Cadmean letters.
Source: Webster's dictionaryIt was a kind of Cadmean victory. Herodotus
In fighting and killing the snake, the companions of the founder Cadmus all perished - leading to the term " Cadmean victory " (i.e. a victory involving one's own ruin). Source: Internet