Plain English Meaning

Pointed, horn-shaped chunks of ice that grow out of the front edge of the wing or tail. Their shape is especially bad for flying because it spoils the smooth airflow the wing depends on.

Full Definition

Ice formations that build forward and upward from the leading edge of an airfoil into shapes resembling horns, typically formed when supercooled water droplets strike the wing and freeze just aft of the leading edge on the upper and lower surfaces. These shapes severely disrupt airflow, causing large reductions in lift, significant increases in drag, and a sharp drop in stall angle of attack.

Context Anchor

Seen in icing discussions, especially when describing how ice on a wing changes airflow and aircraft handling.