One who tends to interrupt or meddle in others' lives. The term is a play on the phrase "butt in," meaning to intrude or encroach. A: "Mom is constantly trying to fix me up with other people." B: "Ugh, I know, she can be a real buttinsky." Geez, Aunt Connie is such a buttinsky, constantly lecturing me as though she knows what it's like to be a college student today. Can you give us five minutes to talk and stop being such a buttinsky?