From Longman Dictionary of Contemporary Englishlunchboxlunch‧box /ˈlʌntʃbɒks $ -bɑːks/ noun [countable] DFa box in which food is carried to school, work etc
Examples from the Corpus
lunchbox• Emotional nurturing may occur at family mealtime, snacks after school, or with notes tucked into lunchboxes.• I suppress an evil wish that an orca will be drawn in by this moving lunchbox of an animal.• Stylish, clear plastic lunchbox with carrying handle, available in clear, red, yellow, purple, blue or pink.• Plant subjects in the same lunchboxes that had been used for previous experiments were placed on a stand and viewed.• They went from the workplace into the canteen, they sat and opened their lunchboxes in their working clothes. 