From Longman Dictionary of Contemporary Englishoverspillo‧ver‧spill /ˈəʊvəˌspɪl $ ˈoʊvər-/ noun [singular, uncountable] British English SGpeople who move out of a big city because there are too many people living there, and go to live in new houses outside the city an overspill of workers from London
Examples from the Corpus
overspill• The heart of the strong population growth lay in London itself and an overspill of about 1 million people was expected.• The 144 cells are now used as an overspill for Wormwood Scrubs.• Female speaker it will be terrible there is bound to be overspill and vandalism.• The farm itself housed twenty-five Czechoslovaks who were part of the overspill from Whittingham. 