Definition
A flight control surface mounted on the upper surface of the wing that, when raised, disrupts (spoils) the smooth airflow over the wing, reducing lift and increasing drag. Spoilers are used to steepen descent rates, slow the airplane, assist roll control, and on the ground to dump lift after touchdown so the wheels carry the airplane's full weight for effective braking.
Plain English
A panel on top of the wing that pops up to kill some of the wing's lift on purpose. Pilots use it to come down faster, slow down, help bank the airplane, or plant the airplane firmly on the runway after landing.
Context Anchor
You may encounter spoilers in flight control discussions, descent planning, landing rollout procedures, and airplane systems descriptions.
Derivation
From the everyday verb 'spoil' — to ruin or disrupt. The surface 'spoils' the airflow over the wing, which is exactly what it's designed to do.
Why Pilots Care
Enables a steeper descent without increasing airspeed and shortens landing distance by increasing drag and reducing lift after touchdown.
Intuition Check
Do not read “spoiler” as something that ruins the flight. In this context, it is a control surface that intentionally disrupts airflow over the wing for a useful purpose.
Example Sentence 1
After touchdown, the spoilers deployed automatically, settling the airplane onto its wheels for braking.
Example Sentence 2
After touchdown the spoilers extended automatically to help slow the airplane on the runway.