Pronunciation: (u-pin'yun),[key] —n. 1. a belief or judgment that rests on grounds insufficient to produce complete certainty.
2. a personal view, attitude, or appraisal.
3. the formal expression of a professional judgment: to ask for a second medical opinion. 4. Law.the formal statement by a judge or court of the reasoning and the principles of law used in reaching a decision of a case.
5. a judgment or estimate of a person or thing with respect to character, merit, etc.: to forfeit someone's good opinion. 6. a favorable estimate; esteem: I haven't much of an opinion of him.