Utilitarian Art - Art created primarily for a practical purpose. A quilt, for example, can be a utilitarian artwork.
Ultraviolet (UV) - The light whose wavelength (about 380 nanometers) is long enough not to be x-rays but shorter than violet light, so it is not visible to the human eye. Ultraviolet is also known as the short form of "UV." It is sometimes called black light because ultraviolet lamps (usually mercury-vapor lamps) appear quite dark even when lit and because of the peculiar way it illuminates certain kinds of surfaces, such as Day-Glo colors.
Underdrawing - Drawing preliminary to other work and incorporated into it, thus deprived of independent artistic value. An example is the underdrawing in fresco and panel painting. In fresco painting, a method of transferring a drawing or design to another surface is used. By dabbing pounce (fine powder of charcoal or chalk) through pinpricks marking the outlines of the drawing, the drawing is therefore reproduced on the surface below as a series of dots.
Underpainting - The layer or layers of color on a painting surface applied before the overpainting or final coat. There are many types of underpainting. One type is the all-over tinting of white ground. Another is a blocked-out image in diluted oil paints that guides the painter while developing the composition and color effects. Also see abbozzo, azurite, grisaille, pochade, and sinopia.
Unique - One of a kind, an original.
Unity - Appearance of oneness; the design continuity eliminates confusion. Unity is a principle of design.
Undertone - The appearance of a pigment spread thinly, as opposed to a mass tone.
