A dairy is a farm that specializes in milk and products made from milk. Cheese, yogurt, cream, and ice cream are all things that might be produced at a dairy.
While one kind of dairy is a farm where cows or goats are kept and milked, other dairies focus only on making products from milk that farmers sell to them. These items themselves can also be called dairy products. Dairy comes from the Middle English daie, "dairy," which is rooted in the Old English dæge, "kneader of bread," or "female servant."