Plain English Meaning
A braking system that stops the wheels from skidding when you brake hard. It quickly releases and reapplies the brakes many times a second so the tires keep rolling instead of sliding, which lets you steer and stop more safely.
Full Definition
A wheel-braking system that automatically detects when a wheel is about to lock up under heavy braking and rapidly modulates brake pressure to keep the wheel rolling. By preventing wheel lockup, it preserves directional control and shortens stopping distance on slippery or contaminated runways.
Context Anchor
Seen in landing performance discussions, especially when considering braking action, stopping distance, and directional control after touchdown.
Derivation
From 'anti-' (against) and 'lock' (a wheel that has stopped while the is still moving). The name describes exactly what it does: prevents the wheel from locking.