keep down

Short definition from Wiktionary

Verb

1. 1
   To repress.
2. 2
   To restrain or control (a sound).
3. 3
   To cause not to increase or rise.
4. 4
   To retain in the stomach without vomiting.
5. 5
   To lie low; to stay concealed by not standing up.
6. 6
   To refrain from using capital letters more than absolutely necessary.