Your opinion is your view, belief, or judgment. If you are opinionated, you obstinately hold on to your opinions, and you don't hesitate to let other people know what those opinions are.
Opinionated is based on the word "opinion," which itself comes from the Latin word opinari, meaning to think. If you and your sister are both extremely opinionated, it must have been hard growing up in the same house — for you and for your parents. Someone who is not at all opinionated can be just as frustrating to live with, though, if their response always seems to be, "I don't care."
