(1):

(n.) A pustule; a whelk.

(2):

(n.) A more or less elongated mark raised by a stroke; also, a similar mark made by any cause; a weal; a wale.

(3):

(n.) Specifically (Med.), a flat, burning or itching eminence on the skin, such as is produced by a mosquito bite, or in urticaria.

(4):

(n.) A mine.