Advancing blade

The blade on a helicopter rotor whose tip is moving in the same direction the helicopter is moving.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

Also defined in 1 more source

The blade moving in the same direction as the helicopter. In helicopters that have counterclockwise main rotor blade rotation as viewed from above, the advancing blade is in the right half of the rotor disk area during forward movement.

Helicopter Flying Handbook, p. G-1

Taught in AF-N Concepts.