Merriam-Webster Collegiate Dictionary - mandible

 noun  Etymology: Middle English, from Late Latin mandibula, from Latin mandere to chew; probably akin to Greek masasthai to chew  Date: 15th century  1.  a. jaw 1a; especially a lower jaw consisting of a single bone or of completely fused bones  b. the lower jaw with its investing soft parts  c. either the upper or lower segment of the bill of a bird  2. any of various invertebrate mouthparts serving to hold or bite food materials; especially either member of the anterior pair of mouth appendages of an arthropod often forming strong biting jaws  • mandibular adjective  • mandibulate adjective