What does 幻想 mean?
幻想 is a Japanese noun meaning “fantasy; illusion; vision; dream” in English. It is written as 幻想 in kanji, げんそう in hiragana, and gensou in romaji. This word is part of JLPT N3 vocabulary.
Example sentence
あなたの考えはいわば幻想にすぎません。
Your idea is, as it were, a castle in the air.