The term arose from the generalization of a specific fabric called Blanket fabric, a heavily napped woolen weave pioneered by Thomas Blanket (Blanquette), a Flemish weaver who lived in Bristol, England, in the 14th century. Earlier usage of the term is possible through its derivation from the French word for white: blanc. According to the Oxford English Dictionary, the word was used a noun as long ago as the 14th century. William Shakespeare is recognised as the first person to use the verb Blanket, meaning to 'cover with or as with a Blanket'.
In the play King Lear, published in 1608, the character Edgar says: "My face ile grime with filth, Blanket my loynes, else all my haire with knots."