Oakley, Violet: Violet Oakley was an American painter who was born in 1874 and lived until 1961. She was a skilled portrait artist, illustrator, muralist and maker of stained glass. She is famous for the 43 murals she painted for Pennsylvania's state capitol, which cover the founding of Pennsylvania.

-Wikipedia

Objective Art: Objective Art is based on physical actuality or optical perception. This art appears natural or real.

-Art Fundamentals

Oblique Projection: Oblique Perception is a technical drawing technique where a three-dimensional object is represented two-dimensionally. The front and back sides of the object are parallel to the horizontal base, where the other planes are drawn as parallels coming off the front plane at forty-five degree angles.

-Art Fundamentals

Oil Pastels: Oil Pastels are a combination of pigments, oils and waxes, formed in the shape of a short, crayon-like cylinder wrapped in paper. They are vibrant like oil paints, but less messy and more convenient to use, like wax crayons.

-L.M. Hornberger: Oil Pastel

Op Art: Op Art is a type of absract art that has a direct impact on the physiology and psychology of vision or sight. This art style was begun in the 1950's.

-Art Fundamentals

Open-Value Composition: An open-value composition allows values to cross over shape boundaries into nearby areas.

-Art Fundamentals

Organic Unity: Organic Unity states that subject, form, and content are so vital and interdependent that they are synonymous with a living organism.

-Art Fundamentals

Orthographic Drawing: Orthographic Drawing is a graphic representation of two-dimensional views of an object, showing a plan, vertical elevations, and/or a section.

-Art Fundamentals