You know how it goes. I was curious, so I looked it up.
o·pin·ion
/əˈpɪn
yən/
Show Spelled[uh-pin-yuh
–noun
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.
While researching I also found this:
Opinion, sentiment, view are terms for one’s conclusion about something. An opinion is a belief or judgment that falls short of absolute conviction, certainty, or positive knowledge; it is a conclusion that certain facts, ideas, etc., are probably true or likely to prove so: political opinions; an opinion about art; In my opinion this is true. Sentiment (usually pl.) refers to a rather fixed conviction, usually based on feeling or emotion rather than reasoning: These are my sentiments. View is an estimate of something, an intellectual judgment, a critical survey based on a mental examination, particularly of a public matter: views on governmental planning.
So, in my opinion, while I’m arguing what I believe to be my opinion, you are arguing what you believe to be fact.
I respect your opinion.
Can you respect mine?
Agreycat 
love