"Tongue," as a noun, comes from the Old Englishtunge meaning "the principal organ of taste," which is what it means now. By the 1560's it started to mean "any object resembling a tongue" (see Acts 2-3, "And there appeared unto them cloven tongues like as of fire, and it sat upon each of them."). Used as a verb it meant "to lick" by the 1680's. Slang from the 1800s includes the phrase "tongue-bang" meaning "to scold heartily." Links.NightCafe Image Source