"Nil by mouth"
When some-one cannot swallow they may not be allowed to eat or drink anything in case it goes down the wrong way into the lungs.
"Nil by mouth" is the sign put above the bed of some-one who, for whatever reason, has been told they should not eat or drink anything. It is to remind those caring for them that they should not be giving them anything. This may happen in the case of people who cannot swallow after a stroke. The main problem is that people can get very hungry and thirsty, so this should not last for longer than 24 hours without some action being taken to ensure that the patient receives adequate food and water by other means.
