blanco
Concise Oxford English Dictionary © 2008 Oxford University Press:
blanco /ˈblaŋkəʊ/ Brit.
▶noun a white substance used for whitening belts and other items of military equipment. ▶verb (blancoes, blancoing, blancoed) whiten with blanco.
– origin C19: from Fr. blanc ‘white’, ult. of Gmc origin.
'blanco' also found in these Oxford entries:

