The term 'potato, informally' can be expressed in two different ways. The first is 'SPUD', which is a four-letter word. This term is believed to have originated in the 16th century and is derived from the Dutch word 'spoet', meaning 'a sharp stick'. The second term is 'TATER', which is a five-letter word. This term is believed to have originated in the 19th century and is derived from the Southern American dialect of English. Both terms are used to refer to potatoes informally.