弁当
べんとう · bentou · JLPT N3 · noun
lunch
🍱 From Chinese 便當 biàndāng, convenient: a lunch that is handy to carry
Japanese borrowed the Southern Song slang word 便當, meaning convenient, and later wrote it as 弁当. So a bentou is the convenient meal, packed in a box so it travels with you.
当 — small ⺌ + crown 冖 + hand 彐 (simplified from 當: 尚 + 田)
Originally written 當, combining 田 'field' with 尚 as a phonetic. The early sense was 'to match' or 'face' a field of equal value, extended to 'correspond to', 'ought to', and 'serve as'. The simplified form 当 streamlines the upper 尚 component.