Genital herpes: An infection by human herpes virus that is transmitted through intimate contact with the moist mucous linings of the genitals. This contact can involve the mouth, the vagina, or the genital skin. Following infection, the virus travels to nerve roots near the spinal cord and settles there permanently. When an infected person has a herpes outbreak, the virus travels down the nerve fibers to the site of the original infection; when it reaches the skin, redness and blisters occur. Commonly called herpes.