What does 異性 mean?
異性 is a Japanese noun meaning “the opposite sex” in English. It can also be translated as “isomerism” depending on context. It is written as 異性 in kanji, いせい in hiragana, and isei in romaji. This word is part of JLPT N1 vocabulary.
Example sentence
彼女は異性の前では非常に恥ずかしがる。
She feels very shy in the presence of the opposite sex.