gesso

noun, plural ges·soes.

1. gypsum or plaster of Paris prepared with glue for use as a surface for painting.
2. any plasterlike preparation to prepare a surface for painting, gilding, etc.
3. a prepared surface of plaster or plasterlike material for painting, gilding, etc.

noun

1. a white ground of plaster and size, used esp in the Middle Ages and Renaissance to prepare panels or canvas for painting or gilding
2. any white substance, esp plaster of Paris, that forms a ground when mixed with water