Rotation
When viewed from the stern (facing forward): Right-hand propellers rotate clockwise to provide forward thrust. Left-hand propellers rotate counter-clockwise to provide forward thrust.

Skew
The transverse sweeping of a blade such that viewing the blades from fore or aft shows an asymmetrical shape.
Aft Skew: Positive skew. Blade sweep in direction opposite of rotation.
Forward Skew: Negative skew. Blade sweep in same direction as rotation.

Slip
Slip is the difference between actual and theoretical travel of the propeller blades through water. A properly matched propeller will actually move forward about 80 to 90 percent of the theoretical pitch.