iodine

(noun) a nonmetallic element belonging to the halogens; used especially in medicine and photography and in dyes; occurs naturally only in combination in small quantities (as in sea water or rocks). Synonyms: iodin, I, atomic number 53.

(noun) a tincture consisting of a solution of iodine in ethyl alcohol; applied topically to wounds as an antiseptic. Synonyms: tincture of iodine.