Plain English Meaning
A tiny bulge inside your inner ear that senses when your head turns. Fluid sloshing inside it bends little hairs, and those hairs tell your brain you are turning.
Full Definition
A small, fluid-filled enlargement at the base of each semicircular canal in the inner ear, containing sensory hair cells that detect angular acceleration of the head. When the head rotates, fluid movement within the canal bends the hair cells inside the ampulla, generating nerve signals the brain interprets as turning motion.
Context Anchor
Seen in spatial disorientation discussions and diagrams of the inner ear, especially when explaining why a pilot can feel a turn that is not actually happening.
Derivation
From Latin ampulla, meaning a small flask or bottle. The structure was named for its shape — a rounded swelling at one end of each semicircular canal, resembling a little bottle.