to crush hard food loudly between the teeth, or to make a sound as if something is being crushed or broken:
She was crunching noisily on an apple.
The gravel crunched underfoot as we walked up to the house.
adjective
(informal) a crunch meeting, sports game, etc. is very important and may be the last chance to succeed （会议、体育竞赛等）至关重要的，最后一线胜机的
Sunday’s crunch game with Leeds
星期天与利兹队决一雌雄的比赛