MedGen

A sensation of unease in the stomach together with an urge to vomit. [from HPO]

Nausea is a commonly encountered symptom that has been defined as an unpleasant painless subjective feeling that one will imminently vomit. Vomiting has been defined as the forceful expulsion of the contents of the stomach, duodenum, or jejunum through the oral cavity. While nausea and vomiting are often thought to exist on a temporal continuum, this is not always the case. There are situations when severe nausea may be present without emesis and less frequently, when emesis may be present without preceding nausea. [from HPO]

Forceful ejection of the contents of the stomach through the mouth by means of a series of involuntary spasmic contractions. [from HPO]