What does OPINION mean?

noun

1. a personal belief or judgment that is not founded on proof or certainty“my opinion differs from yours”
2. 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“his opinions appeared frequently on the editorial page”
3. a belief or sentiment shared by most people; the voice of the people“he asked for a poll of public opinion”
4. the legal document stating the reasons for a judicial decision“opinions are usually written by a single judge”
5. the reason for a court's judgment (as opposed to the decision itself)
6. a vague idea in which some confidence is placed“his impression of her was favorable”