From Longman Dictionary of Contemporary Englishcanvascan‧vas /ˈkænvəs/ ●●○ noun 1 [uncountable]TIM strong cloth used to make bags, tents, shoes etc a canvas bag2 
[countable]AVP a painting done with oil paints, or the piece of cloth it is painted on The gallery has a canvas by Paul Cézanne. ‘Four Women on a Bench’, oil on canvas, 19913 → a broader/wider/larger canvas4 → under canvas
[countable]AVP a painting done with oil paints, or the piece of cloth it is painted on The gallery has a canvas by Paul Cézanne. ‘Four Women on a Bench’, oil on canvas, 19913 → a broader/wider/larger canvas4 → under canvasExamples from the Corpus
canvas• And from somewhere beneath a cupboard she produced an enormous canvas draped in a sheet and showed it to me.• Some artists prefer the springy sensitivity of an open canvas whilst others prefer the hardness or smoothness of a board.• Painting on wall or canvas as dream of plenitude, painting on glass as revelation of potential in poverty.• This was not the fluid, precise canvas of the Cal victory.• He tried out the Helen Frankenthaler technique of staining raw canvas with diluted paint.• He had brought the canvas bag with him.• The man in the canvas chair threw his Daily Variety to the floor.Origin canvas (1300-1400) Old North French canevas, from Latin cannabis “hemp” 