Gresham's law
Concise Oxford English Dictionary © 2008 Oxford University Press:
Gresham's law/ˈɡrɛʃ(ə)mz/
▶noun Economics the tendency for money of lower intrinsic value to circulate more freely than money of higher intrinsic and equal nominal value (often expressed as ‘Bad money drives out good’).
– origin from the name of the 16th-cent. English financier Sir Thomas Gresham.
'Gresham's law' also found in these Oxford entries:

