To move or point in the direction between south and west.
When something southwests, it is going in the direction between south and west.
Examples:
The airplane southwests towards its destination.
The compass needle southwests when we travel.
She walks and southwests at the same time.
The bird southwests to find a warm place.
The river southwests through the valley.
The wind southwests, making the trees sway.