異性

• Reading: いせい
• Romaji: isei
• Kanji breakdown: 異 (i) — different, unusual; 性 (sei) — sex, gender, nature
• Pronunciation: /i.seː/

Meaning

The opposite sex. A person of a different gender from oneself.

A noun referring to people of the opposite sex. Commonly appears in patterns like 異性の友達 (friends of the opposite sex), 異性に興味がある (to be interested in the opposite sex), and 異性関係 (relationships with the opposite sex). A relatively neutral, clinical term compared to more casual alternatives. Also functions as a no-adjective (異性の).

Examples

1. 異性の友達と二人で旅行するのは普通のことだ。 Traveling alone with a friend of the opposite sex is perfectly normal.
2. 思春期になると異性を意識し始める。 During puberty, people start becoming aware of the opposite sex.
3. 彼は異性に対してとても紳士的な態度をとる。 He behaves in a very gentlemanly manner toward the opposite sex.

Usage Guide

Context: relationships, psychology, social discussions

Tone: neutral

Origin & History

From Sino-Japanese 異 (i, different/other) + 性 (sei, sex/nature). Literally 'different sex,' a direct and neutral way to refer to the opposite gender. Parallels 同性 (dōsei, same sex).

Cultural Context

Era: Modern

Generation: All ages

Social background: Universal