On the breadline means to be living in poverty, or to have an income that is only just enough for survival. British English.
A breadline (North American English) is a queue of people waiting to receive food given by a charity.
Examples of use:
a) News headline: Britain on the breadline: families join food queue.
b) Mr and Mrs Pinter have lost their jobs, and now the whole family is living on the breadline.
c) Many elderly people live on the breadline.
d) News headline: Europe on the breadline: Greeks and Italians blame culture of corruption.
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