opinion

1250–1300; Middle English < Old French < Latin opīniōn- (stem of opīniō), derivative of opīnārī to opine

1. 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.

English opinion comes from Middle English opinion, openyoun, from Anglo-French opinion, oppinion “view, belief,” later “reputation” and “intention, judgment.”
The French comes from Latin opīniō (inflectional stem opīniōn- ), which has all of the French senses, vague as they are (in that they refer to belief as opposed to fact or truth). Opīniō is a derivative of the verb opīnārī “to suppose, imagine, conjecture.”
The English noun ranges in meaning from a personal belief resting on grounds incapable of proof, to the formal statement of a court or judge of the reasoning and principles of law used in reaching a decision, to the expert opinion of a physician or other professional, as well as continuing the vague meanings of French and Latin.
The terms opinion poll and opinion polling date from about 1940, although poll in the sense “a survey of public opinion on an issue” appeared around the turn of the 20th century.