noun
mere child's play; trivial matter
Literary or formal term used to dismiss something as trivial, childish, or beneath consideration. Often appears in the phrase 児戯に等しい (equivalent to child's play).
彼の議論など児戯に等しい。
His argument is nothing more than child's play.
そんな計画は児戯に過ぎない。
Such a plan is mere child's play.