tank used for collecting and storing a liquid (as water or oil)
lake used to store water for community use
anything (a person or animal or plant or substance) in which an infectious agent normally lives and multiplies; "an infectious agent depends on a reservoir for its survival"
a large or extra supply of something; "a reservoir of talent"
any warm-blooded vertebrate having the skin more or less covered with hair; young are born alive except for the small subclass of monotremes and nourished with milk