brown-bag lunch
nounUK /ˌbraʊnˈbæɡ lʌntʃ/
US /ˌbraʊnˈbæɡ lʌntʃ/
A lunch you bring from home in a bag.
I packed a brown-bag lunch with a sandwich and an apple.
OTHER MEANINGS
2. A simple lunch eaten at work or school instead of going out.
We had a brown-bag lunch in the meeting room.
3. To bring your own lunch from home.
She brown-bags it every day to save money.
4. A plain, no-frills meal.
The conference offered a brown-bag lunch for attendees.