noun
lunchbox hanging from one's waist; low-paid office worker
Originally referred to a lunchbox tied to the waist, then came to mean a low-ranking, poorly paid office worker who brings a lunchbox. The term is dated and carries a slightly derogatory or pitying tone.
昔の腰弁は、昼になると腰に下げた弁当を広げたものだ。
In the old days, low-paid office workers would open their lunchboxes hanging from their waists at noon.
彼は長年腰弁暮らしで、なかなか昇進できなかった。
He lived as a low-paid office worker for many years and couldn't get promoted.