うち・内・中uchi[0]heiban (flat)

1. noun, adverbinside; within
2. noun, adverbwhile (e.g. one is young); during; within (e.g. a day); in the course of
   あの少年しょうねんは店みせから店みせを歩あるいているうちに盗み癖ぬすみぐせがでてしまった。↗

   The young boy got sticky fingers when he walked into stores.

   エイズが私が生いきているうちに治なおることを願ねがっているよ。↗

   I have a dream that AIDS will be cured in my lifetime.
3. noun, adverbamong; amongst; (out) of; betweenas 〜のうち
   私の息子むすこ二人ふたりのうち、一人ひとりは教師きょうしで、もう一人ひとりは医者いしゃです。↗

   One of my sons is a teacher, and the other is a doctor.

   教会きょうかいは私の家うちとあなたの家うちの中なかにあります。↗

   The church is between my house and yours.
4. nounin (secret, chaos, poverty, etc.); amidst; with (e.g. success)also 裡, 裏; as 〜のうちに after a noun representing a state or condition
5. nounwithin oneself; one's feelings; inner thoughts
6. nounwe; our company; our organization
   うちの一番いちばん腕利うでききの交渉者こうしょうしゃはいつも強引ごういんに有利ゆうりな取り引とりひきをする。↗

   Our best negotiators always drive a hard bargain.

   「うちで働はたらいてみたいかね」とウッドさんが尋たずねました。↗

   "Would you like to work for me, Tony?" asked Mr Wood.
7. nounone's home; one's familyalso 家
8. nounmy spouse; my husband; my wife
9. nounsigned on behalf of (husband's name) by his wifein a letter after the husband's name
10. pronounI; meprimarily used by women and children
11. nounimperial palace grounds
12. nounemperor

• Synonym内部ないぶWrittenWritten/formal prose word for the inside of a building or organization, as in 「内部情報」 or 「建物の内部」; more formal than 「内」.
• Synonym内側うちがわNeutralNeutral word for the inward-facing side of something, as in 「箱の内側」; it stresses direction rather than the space as a whole.
• Synonym内ないWrittenRead 「ない」, it works mostly as a suffix marking the bounds of a range, as in 「社内」 or 「期限内」; leans written, though compounds like these are common in speech too.
• SynonymインサイドCasualColloquial loanword for the inner side or inside corner, mostly in sports, as in 「インサイドキック」.
• RelatedインナーCasualColloquial loanword that usually means underwear or an inner layer, as in 「インナーウェア」.
• Antonym外そとNeutralNeutral antonym of 「内」: the outside or exterior, as in 「家の外で遊ぶ」.

For inside or within, 「内」 is the default. Use 「内部」 for the inside of an organization or structure, 「内側」 for the inward-facing side, the suffix 「〜内」 for ranges like 「社内」, and 「外」 for the outside.

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

1. （うち）建物たてものなど閉とじた空間くうかんの中なか。
2. （うち）一定いっていの期間きかん。