Plain English Meaning

A skid is when the airplane's tail slides out toward the outside of a turn because too much rudder is being used for the amount of bank. The airplane is turning too fast for how much it is leaning.

Full Definition

A skid is a turning error in which the airplane's tail swings to the outside of the turn because the rate of turn is too high for the bank angle being held. The airplane is yawing faster than the bank wants to carry it, producing sideways movement away from the center of the turn. It is felt as the pilot being pushed toward the outside of the turn and is corrected by either reducing rudder pressure or increasing the bank.

Context Anchor

Seen during ground reference maneuvers such as a rectangular course, and in any turn where rudder and bank are not balanced.