A prohibition or taboo; something that is forbidden or at least discouraged. The term dates from the mid-1900s and was popularized in the late 1960s in a television show, Rowan & Martin’s Laugh-In. Danielle and John Kinkel used it in the Boston Globe (Feb. 24, 2005) in a piece about the shortage of Roman Catholic priests: “First, everyone knows that ordaining women is a papal no-no and will not be acted upon in the near future.”