Altering course toward the wind.
Pointing the boat into the wind - sail flapping.
A description of a flapping motion along the luff (leading edge) of a sail. A sail begins to luff when the air flow stalls when traveling across the sail. Luffing is a sign that the sail is not properly trimmed or that the you are trying to sail too close to the eye of the wind (pinching.)
luffing occurs when the airflow stalls when travelling across the sail.