A misconception is a conclusion that's wrong because it's based on faulty thinking or facts that are wrong. Your accusation about your brother's role in that unfortunate event at your party may be based on a misconception.
First appearing in the 1660s, the noun misconception comes from the prefix mis-, meaning "bad, wrong," and the word conception, meaning "act of conceiving." A misconception usually results from incorrect thinking or a flawed understanding. Because they don't know the facts, many people have a misconception about how diseases such as AIDS are transmitted. It's a common misconception that Thomas Edison invented the light bulb, when, in fact, he didn't.