背中|せなかsenaka[0]heiban (flat)

1. nounback (of the body)
   このブラウスはボタンが背中せなかにある。↗

   This blouse buttons at the back.

• Synonym背部はいぶWrittenWritten term used mainly in medical contexts and explanatory prose, as in 「背部の痛み」; not the everyday word for one's back.
• Related後ろうしろNeutralRefers broadly to the direction or position behind, not to a specific body part; 「背中」 names a concrete part of the body.
• Related裏面りめんWrittenWritten term for the reverse side of an object or behind-the-scenes matters; not used for a person's back.
• Related裏うらNeutralThe reverse of the front side, or a hidden place behind; not used for a person's back.
• Related裏側うらがわNeutralThe reverse side of an object; also the back of a body part, as in 「膝の裏側」, or hidden facts; for the whole back say 「背中」.
• Related後部こうぶWrittenWritten term for the rear part of a vehicle or object, as in 「後部座席」.
• Related裏手うらてNeutralMostly the back of a building, as in 「家の裏手」.
• Related背面はいめんWrittenWritten term for the back of an object, such as the rear of a machine; also a hidden side of something.
• RelatedバックNeutralLoanword mostly for the rear, background or backing/support; its range of use is broader than 「背中」.
• RelatedリアNeutralLoanword mostly for the rear of a vehicle, as in 「リアウインドウ」; not used for the human body.
• Related後ろ側うしろがわNeutralThe rear side of an object; unlike 「背中」 it is not specific to the body.
• Related後背こうはいWrittenMostly used as a prefix in compounds like 「後背地」; rarely stands alone in everyday speech.
• Antonym胸むねNeutralThe front of the body, opposite the back, as in 「胸と背中」.
• Antonym前面ぜんめんNeutralThe front-facing side of an object, the opposite of 「背」 in front-and-back position.

For the human back, 「背中」 is the everyday word; 「背部」 is the written, medical term. For the reverse side of objects use 「裏」「裏側」「背面」, and for the direction behind use 「後ろ」. 「バック」 and 「リア」 are loanwords for the rear, background and vehicle rears; 「胸」 and 「前面」 name the front side.

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

1. 背せ。胴どうの後ろ側うしろがわのうち、腰こしより頭あたまに近ちかい部分ぶぶん。胸むねと腹はらの反対はんたい側がわ。せな。
2. ものを人ひとや動物どうぶつ（の胴どう）に見立みたてたときの背中せなかに当あたる部分ぶぶん。
3. 服ふくや道具どうぐの中なかで、人ひとの背中せなかに接せっする部分ぶぶん。