Gasterosteiformes is an order of ray-finned fishes that includes the sticklebacks and relatives. In the Gasterosteiformes, the pelvic girdle is never attached to the cleithra directly, and the supramaxillary, orbitosphenoid, and basisphenoid bones are absent. The body is often partly or completely covered with dermal plates. The name "Gasterosteiformes" means "bone-bellies". It is derived from Ancient Greek gaster (γαστήρ; "stomach", "abdomen") + ostoun (ὀστοῦν; "bone"). The ending for fish orders "-formes" is derived from Latin and indicates "of similar form".