What does 妄想 mean?
妄想 is a Japanese noun meaning “delusion; wild idea; (wild) fancy; (ridiculous) fantasy” in English. It is written as 妄想 in kanji, もうそう in hiragana, and mousou in romaji. This word is part of JLPT N2 vocabulary.
Example sentence
あの少女は自分が王女様だという妄想にとらわれている。
That girl is under the delusion that she is a princess.