go under

present singular third person goes under · participle present going under · past went under · participle past gone under

1. To descend into a body of water; to founder.

   The boat was too heavy and went under.

2. idiomaticTo 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.

3. idiomaticTo die.

   If we don't get him to a doctor, he'll go under for sure.

   1 more example

   Good for a fortnight, am I? The doctor told you? He lied. I shall go under by morning, and—— Put that nurse outside.

   1896, Rudyard Kipling, The Mary Gloster

4. idiomaticTo be named; to call oneself.

   He goes under the name of Mr X to remain anonymous.

5. To enter a trance, state of hypnosis, etc.

   "But I went under nicely and I am glad there were some fine materializations."

   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

6. AustraliaslangTo be imprisoned.