The word "mandible" refers to the lower jawbone in humans and many other animals. It is the bone that connects to the skull and holds the teeth. Full definition
The new fossil — two inches of mandible with several teeth attached, assigned to the species Homo antecessor — is about 1.2 million years old. (discovermagazine.com)
The game makes good use of the 3DS» namesake feature, as Metroids hurtle through background scenery before bursting onto the front layer and charging our heroine with mandibles agape. (quillstreak.com)
The lower mandible actually curves slightly up, which likely gives it the strength it needs to hold the tool. (sciencedaily.com)