Definition of Lateral

Lateral: 1. In anatomy, the side of the body or a body part that is farther from the middle or center of the body. Typically, lateral refers to the outer side of the body part, but it is also used to refer to the side of a body part. For example, when referring to the knee, lateral refers to the side of the knee farthest from the opposite knee. The opposite of lateral is medial.
2. In radiology, slang for a lateral X-ray.

For a more complete listing of terms used in medicine for spatial orientation, please see the entry to "Anatomic Orientation Terms".