What is the definition or description of: hyperemesis gravidarum?

Morning sickness: Often, particularly in early pregnancy, women will vomit. Sometimes in the morning, sometimes all day or night long. Hyper (increased or large) emesis (vomiting) gravidarum (the condition of being pregnant) literally means increased vomiting of pregnancy and when vomiting exceeds the ability to take in the amount of fluid that's lost then mom needs medical attention and sometimes hospitalization.