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.

Did you mean underpinning?