1Comprehensively observed or studied; widely noted; accurately recorded.
2Of a method, rule, custom, principle of action, etc.: strictly or widely upheld or kept.
3Of an artistic representation of something: skilfully depicted, well drawn, realistic. Hence (of an event or character in a piece of fiction, dramatic performance, etc.): realistically or skilfully portrayed; accurately represented.
Mid 16th century; earliest use found in John Foxe (?1517–1587), martyrologist. From well+ observed.