Impasto
Etymology
From Italian "impasto," "dough, paste, mixture," from impastare, "to make into paste," from in-, "into," and pasta, "paste, dough." The kitchen word for kneaded dough transferred to the studio for paint applied in thick, doughy strokes. It names both the technique and the raised ridges of paint it leaves behind.
noun · /im-PASS-toh/
Paint laid on so thickly that the brush or knife strokes stand up from the surface.
What it names
The ridged, sculptural buildup of pigment in a Van Gogh sky, where the paint itself becomes texture, giving you a word for the physical substance of a painting as opposed to its image.
Example
Up close the sunflowers dissolve into pure impasto — great gobs of yellow you could almost peel off the canvas.
Related idea
Impasto builds paint up into thick, raised texture; a glaze is a thin, transparent film of color laid over what is already there.