When something is "sound," it is trustworthy. A "sound" boat has a solid structure. Unsound opinions are ones that are unsupported by research or evidence, or easily contradicted.
Opinion is what a person thinks about something. For instance, my opinion is that mushrooms are disgusting and inedible. Someone else might love them.
When it is compared to fact, it is usually seen...
It would be more correct to say "Everybody has his/her opinion."
The use of their in this sentence would be correct, though it is widespread in American speech. Originally, one would say "Everybody...
Both are accepted, but after a search on Google you get: 'opinion about': 1,220,000,000 results 'opinion on': 10,160,000,000 results So according to Google 'opinion on' is used about ten times more...