Source : Webster's Revised Unabridged Dictionary (1913)

Plectognathi \Plec*to"gna*thi\, n. pl. [NL., from Gr. ? twisted
   (fr. ? to plait, twist) + ? jaw.] (Zo["o]l.)
   An order of fishes generally having the maxillary bone united
   with the premaxillary, and the articular united with the
   dentary.

   Note: The upper jaw is immovably joined to the skull; the
         ventral fins are rudimentary or wanting; and the body
         is covered with bony plates, spines, or small rough
         ossicles, like shagreen. The order includes the
         diodons, filefishes, globefishes, and trunkfishes.

Source : WordNet®

Plectognathi
     n : boxfishes; filefishes; globefishes; ocean sunfishes;
         triggerfishes; puffers [syn: {order Plectognathi}, {order
         Tetraodontiformes}]