widow's weeds
Concise Oxford English Dictionary © 2008 Oxford University Press:
widow's weeds
▶plural noun black clothes worn by a widow in mourning.
– origin C18 (earlier as mourning weeds): weeds (obs. in the general sense ‘garments’) is from OE wǣd(e), of Gmc origin.
'widow's weeds' also found in these Oxford entries:

