A "white duvet" refers to a bed covering that is white in color. It's a simple way to describe a blanket or comforter that goes on top of a bed. Full definition
I received this set in white duvet cover with pillow cases and immediately washed them The fabric has a super feel: silky soft ultrasuede type. (nymag.com)
This crisp white duvet cover is embroidered with a jewel - toned version of Tiffany Blue, and it can be monogrammed in the centre of the duvet as well. (styleathome.com)
White Bunting Accordion Wall Sconce «Start with Yes» Print Pillowfort Bed Live Edge Side Table «X» Sheet Set Blue Ombre Pillow Fox Zebra Blue Throw Blanket White Duvet Set Beadboard Live Edge Side Table (stylebyemilyhenderson.com)