What does "tetrodon" mean?

Tetrodon: Any one of numerous species of plectognath fishes belonging to Tetrodon and allied genera. Each jaw is furnished with two large, thick, beaklike, bony teeth. [Written also tetradon.] Note: The skin is usually spinous, and the belly is capable of being greatly distended by air or water. It includes the swellfish, puffer (a), and similar species.