A nurse recently told me that i looked dehydrated. what does that even mean?

Dehydration: Dehydration can be dangerous. One of the easiest way to know one is dehydrated is to feel around your mouth with one's tongue to feel how moist one's oral mucosa is. Another way to tell is to look at the urine and see if it is clear (well hydrated) or very concentrated and yellow (dehydrated). Sometimes being dehydrated can affect one's skin turgor. Try some isotonic rehydration (gatorade).