Plain English Meaning

Slotted means the flap has a small gap built into it. When the flap drops down, air sneaks through that gap and flows over the top of the flap, which keeps the air attached and helps the wing make more lift.

Full Definition

A flap design feature in which a narrow gap, or slot, is formed between the leading edge of the deflected flap and the trailing edge of the wing. When the flap is extended, high-pressure air from beneath the wing flows through this slot and over the upper surface of the flap, energizing the airflow and delaying separation. This allows the flap to produce more lift at higher deflection angles than a plain or split flap.

Context Anchor

Seen in discussions of flap types and flap effectiveness, especially when comparing plain, split, slotted, and .