1. （商行等）倒闭，垮掉；（项目）中止，失败
[…]nbsp;[…]nbsp;[…]nbsp;[…]nbsp;If a business or project goes under, it becomes unable to continue in operation or in existence.

2. （船）沉没；（人）沉入水中
[…]nbsp;[…]nbsp;[…]nbsp;[…]nbsp;If a boat, ship, or person in a sea or river goes under, they sink below the surface of the water.