A lunch box is a small container with a lid. You put food such as sandwiches in it to eat for lunch at work or at school. He rode to work on his bike and carried a lunch box. a meal eaten in the middle of the day, or the food prepared for this meal: [ U ] We had soup and sandwiches for lunch. A lunch box (or lunchbox) is a hand-held container used to transport food, usually to work or to school. It is commonly made of metal or plastic, is reasonably airtight and often has a handle for carrying. I take my lunch box to my school. My lunch box was gifted to me by my dad. I love having lunch in my lunch box. Everybody in my class likes my lunch box.