1. (Anat.) The bone, or principal bone, of the lower jaw; the inferior maxilla; -- also applied to either the upper or the lower jaw in the beak of birds.
2. (Zoöl.) The anterior pair of mouth organs of insects, crustaceaus, and related animals, whether adapted for biting or not.
She dreamed of the country of India, where she had never been. There were orange traffic cones and beautiful lapis lazuli insects with mandibles of gold.
Alice Sebold. The Lovely Bones, p.173 (2002)
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behind him, M. de Palancy, who with his huge carp's head and goggling eyes moved slowly up and down the stream of festive gatherings, unlocking his great mandibles at every moment as though in search of his orientation, had the air of carrying about upon his person only an accidental and perhaps purely symbolical fragment of the glass wall of his aquarium,