food that has been chewed and mixed in the mouth with saliva. Chewing helps to reduce food particles to a size readily swallowed; saliva adds digestive enzymes, water, and mucus that help chemically to reduce food particles, hydrate them for taste, and lubricate them for easy swallowing. The term bolus applies to this mixture of food and solutions until they are passed into the stomach. Once the bolus reaches the stomach, mixes with gastric juices, and becomes reduced in size, the food mass becomes known as chyme.