Final answer:
The term 'ingestion' describes the process of food coming in direct contact with the mouth, where it's mechanically and chemically broken down into smaller molecules.
Step-by-step explanation:
The term that matches the description 'In direct contact with ingested food' is ingestion. Ingestion is the initial step in the digestive process where food is taken into the mouth and begins to undergo mechanical and chemical digestion.
This involves breaking down the food into smaller pieces via mastication or chewing, and mixing it with saliva, which contains digestive enzymes. The food, now a softened mass or bolus, is then ready to be swallowed and travel down the esophagus towards the stomach for further digestion.