Varicose veins are visible, protruding veins that appear just under the skin. The word "varicose" comes from the Latin root varix for "twisted." Varicose veins can occur in clusters or look like spider webs, they may also be large, single veins that are easily visible. Although this can occur in any part of the body, it usually develops in the legs. Varicose veins come on with advancing age and are often no great inconvenience apart from being unsightly.