The word "sap" primarily refers to the fluid that circulates in the vascular system of a plant, carrying nutrients and water. It can also be used as a verb meaning to drain someone or something of energy, vitality, or strength. In informal contexts, it can describe a person who is easily deceived or taken advantage of.
The word "sap" comes from Old English "sæpp," which means "juice" or "fluid," related to the Latin word "sapa," meaning "grape juice" or "must." It has evolved through the centuries to encompass both the plant fluid and its figurative uses in the English language.