out of bounds
Beyond established limits, breaking the rules, unreasonable. For example, Calling the teacher a liarthat's out of bounds. This expression alludes to the boundaries of the playing area in numerous sports and to the rules applying to them. Its figurative use dates from the 1940s. [Early 1800s] Also see within bounds.
Dictionary.com presents 366 FAQs, incorporating some of the frequently asked questions from the past with newer queries.