How to say "incest" in Japanese

• インセスト
  nounThe katakana borrowing of English 'incest', identical in meaning. It carries a distinctly foreign flavor, so it fits translated texts or discussion of Western material; in plain Japanese prose 近親相姦 is the safer choice.
• 近親相姦きんしんそうかん
  no-adjectiveThe full Sino-Japanese term, combining 近親 'close relative' with 相姦 'intercourse'; it states the meaning plainly and reads as neutral, serious Japanese, making it the most transparent of the three and the natural first choice.
  議論ぎろんのため、母親ははおやと息子むすこの近親相姦きんしんそうかんが黙認もくにんされている部族ぶぞく社会しゃかいを仮定かていしてみよう。↗

  Imagine, for the sake of argument, a tribal group in which mother-son incest was countenanced.
• 近親姦きんしんかん
  nounA shortened form of 近親相姦 with the same meaning; dropping 相 makes it terser but less immediately recognizable, so unless compactness matters, 近親相姦 is the clearer way to write it.

All three mean sexual relations between close relatives: pick 近親相姦 as the plain Sino-Japanese term, 「インセスト」 when you want the English loanword's foreign flavor, and 近親姦 only as a compact variant of 近親相姦.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• インセストincest
• 近親相姦きんしんそうかんincest
• 近親姦きんしんかんincest
• 畜生道ちくしょうどうincest