To lean, tilt or incline.

“If you slant the track a little more, the marble will roll down it faster.”

To bias or skew.

“The group tends to slant its policies in favor of the big businesses it serves.”

To lie or exaggerate.

The state or quality of being slanted.

“The slanting of the hill was too steep for safe skiing.”

Out of the perpendicular, not perpendicular.