Definition of the word butt in

The phrase "butt in" originated in the 1930s as a slang term to describe someone who suddenly and rudely interrupts a conversation without being invited to do so. The word "butt" in this context has a somewhat derogatory meaning, conveying the idea of a person pushing their way into a situation uninvited. The term "butt in" likely evolved from the expression "butt out," which was used to indicate that someone should stop talking or interfering in a situation. By the 1950s, "butt in" had become a widely recognized term in American English, appearing in popular books, magazines, and newspapers. Its use continued to spread throughout the English-speaking world, and today it is a commonly used idiom meaning to interrupt someone unwantedly.