To behave in a manner appropriate to one's age. / (imperative, originally US) To behave in a mature manner; to avoid being childish.

(idiomatic) Located back at the start, as after a dead end or failure.

(idiomatic) To procrastinate, put off; to dawdle, avoid, or make progress slowly and reluctantly. / (idiomatic) To intentionally stall, to delay, to obstruct.

(slang) Crazy; insane.

when walking or running, to reach a full or comfortable pace / (figuratively) to reach a full level of efficiency, competence, comfort, etc.; to get going

(baseball, dated, slang, 1800s) To throw a curve ball.

(idiomatic) Something of particular interest or concern; an obsession.

(idiomatic, chiefly in the negative) To identify, specify, name or pick out.

(American football) In the AFL, a warning given with one minute to go before the end of a half, after which special rules apply, eg, stoppage of the game clock after very first down.

(bingo) eight