What is excellence?

excellence, n: "The state or fact of excelling; the possession chiefly of good qualities in an eminent or unusual degree; surpassing merit, skill, virtue, worth, etc.; dignity, eminence."

excellent, a.: "Of a person or thing: That excels or surpasses in any respect; preëminent, superior, supreme. Of qualities: Existing in a greater, or an exceptionally great, degree."

OED 2nd Edition 1989