Here is a list a words I have come to know and love in all my glossaries.
Impasto – thickly applied paint which stands out from the surface of a painting
Pastose – paint mixed to a stiff texture, so that it can be used to create impasto
Grisaille -The process of painting in different shades of grey or near-monochrome
Monochrome – A painting done in one color or various shades of one color
Pentimento – Alteration made by the artist to an area already painted. (plural pentimenti) I looked this up in my Italian/English dictionary and it means something like…"I lied, and I regret it."
Medium – the binding agent for pigments in a painting. Drying oils such as linseed, poppyseed, or walnut are used and many times with an addition of a varnish.
Glaze – A layer of translucent paint applied over other paint to modify its colour, or to give depth and richness of colour. A glaze medium is used with a drying oil or drying oil plus varnish.
Primuersel – A thin layer of oil paint applied to the ground before beginning to paint, particularly in the context of a white chalk ground bound in glue for a panel. This layer modifies the colour of the ground and also, in the case of a chalk ground, makes it less liable to absorb oil from the paint layers above. This would be bad because the oil would continue to absorb into the chalk layer and cause irritating "sunk in" or flat (mat) areas of the painting.
Chiaroscuro – From the Italian chiaro light and scuro dark, the depiction of light and shadow in paintings. Beautiful mysterious darks can be achieved using this technique which was first developed by the Italian painter Caravaggio but later associated with the Dutch.
Scumble – A semi-opaque and thin layer of paint applied over a darker dry or nearly dry underlayer. Effects using warm and cool counterpoints can be very striking using this method.
From the glossary of: Art in the Making
gigi was here