The chosen valedictorian is often the student with the highest ranking among his/her graduating class. The term is an Anglicised derivation of the Latin vale dicere (to say farewell), historically rooted in the valedictorian's traditional role as the final speaker at the graduation ceremony.
The human body cannot survive without food and water for long periods of time. In fact, according to SurvivalTopics.com, the longest a person can go without water is 10 days--without food, it's four to six weeks.
Unlike food, the maximum time an individual can go without water seems to be a week. That estimate would certainly be shorter in difficult conditions, like broiling heat. A human can go for more than three weeks without food (Mahatma Gandhi survived 21 days of complete starvation), but water is a different story. At least 60 per cent of the adult body is made of it, and every living cell in the body needs it to keep functioning.