go under

English

go under (third-person singular simple present goes under, present participle going under, simple past went under, past participle gone under)

To descend into a body of water; to founder.
The boat was too heavy and went under.
(idiomatic) To collapse or fail, e.g. by going bankrupt.
In the crisis, the company was forced to reduce its costs in order to avoid going under.
(idiomatic) To die.
If we don't get him to a doctor, he'll go under for sure.
(idiomatic) To be named; to call oneself.
He goes under the name of Mr X to remain anonymous.
To enter a trance, state of hypnosis, etc.
- 1925 July – 1926 May, A[rthur] Conan Doyle, “(please specify the chapter number)”, in The Land of Mist (eBook no. 0601351h.html), Australia: Project Gutenberg Australia, published April 2019:
  "But I went under nicely and I am glad there were some fine materializations."
(slang, Australia) To be imprisoned.

to descend into a body of water

to fail by going bankrupt — see go bankrupt

to be call oneself

to enter a state of hypnosis