период времени(когда есть возможность что-либо сделать; This afternoon, I had a brief window of opportunity when I could discuss this with the boss, but she wasn't receptive. Val_Ships)
возможность(This area of Montana is one of those special places, but we need your help to act quickly before the window of opportunity closes forever. – пока эта возможность ещё не утрачена навсегда
4uzhoj)