Pot meaning to drink is from the 16th century and is a transference of meaning from the pot or vessel in which drink was served. Pot meaning to shoot is from the 19th century and derives from shooting game for the pot, from which we get pot shot. Pot meaning the toilet basin is from the 18th century, from chamber pot. Pot, slang for cannabis, is American from the mid-20th century but its etymology remains obscure. The theory that it derives from potiguaya, a Mexican name for the drug, is very much disputed. See also what’s potting.