Contralateral is a term that references the opposite side of something. 'Contra' means opposite or contrasting while 'lateral' means side. It is usually used in regards to the opposite side of the body from which something occurs. The hemispheres of the brain control the contralateral sides of the body. So the left side of the brain controls the right side of the body and the right side of the brain controls the left side of the body. A stroke that causes damage to the left side of the brain can cause paralysis on the right side of the body.