Plain English Meaning

Tiny tube-shaped channels inside the ear that hold fluid. When the head turns, the fluid shifts and tells the brain which way the body is moving.

Full Definition

Narrow, tube-shaped passages within the inner ear that house the semicircular canals of the vestibular system. Each ear contains three tubular ducts arranged at right angles to one another, filled with fluid that moves in response to head rotation, allowing the body to sense angular motion and maintain balance.

Context Anchor

Seen in discussions of the inner ear, balance, and why pilots can feel false motion during instrument flight.

Derivation

From Latin tubulus, meaning 'small tube,' and ductus, meaning 'a leading' or 'channel.' Together the phrase simply describes small fluid-carrying tubes — which is exactly what these inner-ear structures are.