Abstract is a term often used in art, philosophy, and even science. It describes something that is not concrete or tangible, but rather conceptual or theoretical. Synonyms for the word abstract include intangible, conceptual, theoretical, immaterial, and nonrepresentational. Other possible synonyms include esoteric, philosophical, complex, and obscure. These words all describe ideas, concepts, or concepts that are not easily grasped by the physical senses. In the context of art, abstract art uses shapes, colors, and lines to create compositions that are not meant to represent recognizable objects or scenes, but rather evoke an emotional or sensory response in the viewer.