What does 肉眼 mean?
肉眼 is a Japanese noun meaning “naked eye” in English. It is written as 肉眼 in kanji, にくがん in hiragana, and nikugan in romaji. This word is part of JLPT N2 vocabulary.
Example sentence
それらの星は肉眼で見える、まして望遠鏡ならなおさらである。
You can see the stars with your naked eye, and even better through a telescope.