A verruca is a small, hard, rough lump that grows on the skin of your foot, usually on the sole or the toes. It is caused by a virus, so it can pass from one person to another — which is why people catch them at swimming pools, showers and changing rooms, where bare feet touch wet floors. A verruca often has tiny black dots in the middle and can hurt when you stand or walk on it, because your body weight pushes it inwards instead of letting it stick out. A verruca is really the same thing as a wart; the difference is only where it grows. English speakers say 'wart' for the ones on hands and fingers, and 'verruca' for the ones on the bottom of the foot. Americans mostly do not use this word at all — they say 'plantar wart'. In Britain and in many places that learned English from Britain, 'verruca' is the everyday word, used by parents and school teachers, not just doctors. Doctors also say 'verruca' in a wider way, for warts anywhere on the body, but that is technical use. The plural you will see in careful writing is 'verrucae', though many people simply say 'verrucas'.

足底疣（俗稱雞眼旁邊那種疣；台灣一般講「病毒疣」或「足底疣」，長在腳底的）