Plectognathi n. pl. (Zool.) 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.