内部|ないぶnaibu[1]atamadaka (head-high)

1. no-adjectiveinterior; inside; internal
   この図解ずかいは地球ちきゅうの深ふかい内部ないぶを示しめしている。↗

   The illustration shows the deep interior.

• Synonym内側うちがわNeutralRefers to the inner side, as in 「ドアの内側」; leans toward physical position, while 「内部」 also covers the inside of an organization.
• SynonymうちNeutralMeans the inside, or one's own home or side, as in 「うちの会社」; common in colloquial speech and covers many senses.
• Synonym中なかNeutralAs 「中」, it also covers being within a period of time, as in 「若いうちに」; usually written in kana; overlaps with 「内部」 only in the spatial sense.
• Related内方ないほうWrittenWritten/formal word for the inside; also means another's wife. Rare in modern usage.
• RelatedインサイドNeutralLoanword for the inner side; often heard in sports, as in 「インサイドキック」.
• RelatedインナーNeutralLoanword for underwear or an inner layer, as in 「インナーウェア」; mostly about clothing.
• Related内部的ないぶてきWrittenWritten/formal adjectival form meaning internal to an object or organization; 「内部」 is a noun and can also state a location on its own.
• Antonym外部がいぶNeutralThe outside; the direct opposite of 「内部」, as in 「外部の人」.
• Antonym表面ひょうめんNeutralThe surface; opposite of 「内部」 in the sense of outward appearance versus what lies within.

Use 「内部」 for the inside of a thing or an organization, as in 「内部情報」「建物の内部」. For a physical inner side prefer 「内側」, and in casual talk 「うち」. 「インサイド」 fits sports contexts, 「インナー」 clothing, 「内部的」 is the written adjectival form, and 「外部」「表面」 stand opposite.

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

1. 仕切しきりの中なかの方ほう。
2. 集団しゅうだんの中なか。
3. ある位相いそう空間くうかんと、その位相いそう空間くうかんのある部分ぶぶん集合しゅうごうを考かんがえるとき、その部分ぶぶん集合しゅうごうの全すべての内うち点てんから成なる集合しゅうごう。