The story
From buccal (“of or pertaining to the cheek or mouth”) + cavity (“hollow area”).
Etymology from Wiktionary, CC BY-SA 4.0.
buccal cavity
Today it means: The oral cavity, bound by the cheeks of the face, the palate, and the flesh of the mandible, opening onto the mouth and the fauces, and containing the teeth, tongue, gums, and other structures. Full definition →