opinion

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A belief or conclusion held with confidence but not substantiated by positive knowledge or proof: "The world is not run by thought, nor by imagination, but by opinion” ( Elizabeth Drew).
2. n. A judgment based on special knowledge and given by an expert: a medical opinion.
3. n. A judgment or estimation of the merit of a person or thing: has a low opinion of braggarts.
4. n. The prevailing view: public opinion.
5. n. Law A formal statement by a court or other adjudicative body of the legal reasons and principles for the conclusions of the court.

Century Dictionary and Cyclopedia

1. n. A judgment formed or a conclusion reached; especially, a judgment formed on evidence that does not produce knowledge or certainty; one's view of a matter; what one thinks, as distinguished from what one knows to be true.
2. n. Specifically — The estimate which one forms regarding persons or things with reference to their character, qualities, etc.: as, to have a poor opinion of a man's honesty, or of the efficiency of some arrangement or contrivance; a poor opinion of one's self.
3. n. Favorable judgment or estimate; estimation.
4. n. Judgment or persuasion, held more or less intelligently or firmly; conviction: often in the plural: as, one's political opinions.
5. n. A judgment or view regarded as influenced more by sentiment or feeling than by reason; especially, views so held by many at once, collectively regarded as constituting a social force which tends to control the minds of men and determine their action.
6. n. Common notion or idea; belief.
7. n. Rumor; report.
8. n. A professional judgment on a case submitted for examination: as, a legal or medical opinion.
9. n. Standing in the eyes of one's neighbors or society at large; reputation; especially, favorable reputation; credit.
10. n. Dogmatism; opinionativeness.
11. n. Synonyms Belief, Conviction, etc. (see persuasion); sentiment, notion, idea, view, impression.
12. To think; opine.

Wiktionary

1. n. A belief that a person has formed about a topic or issue.
2. v. transitive, archaic To have or express as an opinion.

GNU Webster's 1913

1. n. That which is opined; a notion or conviction founded on probable evidence; belief stronger than impression, less strong than positive knowledge; settled judgment in regard to any point of knowledge or action.
2. n. The judgment or sentiment which the mind forms of persons or things; estimation.
3. n. obsolete Favorable estimation; hence, consideration; reputation; fame; public sentiment or esteem.
4. n. obsolete Obstinacy in holding to one's belief or impression; opiniativeness; conceitedness.
5. n. (Law.) The formal decision, or expression of views, of a judge, an umpire, a counselor, or other party officially called upon to consider and decide upon a matter or point submitted.
6. v. obsolete To opine.

WordNet 3.0

1. n. a belief or sentiment shared by most people; the voice of the people
2. n. the legal document stating the reasons for a judicial decision
3. n. the reason for a court's judgment (as opposed to the decision itself)
4. n. a personal belief or judgment that is not founded on proof or certainty
5. n. a vague idea in which some confidence is placed
6. n. a message expressing a belief about something; the expression of a belief that is held with confidence but not substantiated by positive knowledge or proof