Sap/sæp/ Definition 1 of 3Pro Tip 1/3Natural Substance Sap refers to a vital liquid that circulates within a plant's structure. After cutting the vine, clear sap began to drip out. Pro Tip 2/3Not Always Edible While some sap is used in food, like maple syrup, not all sap is safe to consume. The sap from this tree is toxic and should not be tasted. Pro Tip 3/3Varied Consistency Sap can range from watery to very thick, depending on the plant species. The sap that oozed from the tree was thicker than honey.