一部分|いちぶぶんichibubun[3]nakadaka (mid-high)

1. nounone part; one portion; one section
   その建物たてものの一部分いちぶぶんだけが地震じしんで破壊はかいされた。↗

   Only part of the building has been destroyed by the earthquake.

• Synonym一部いちぶNeutralA part, as in 「一部の人」 or 「一部の地域」. Very close to 「一部分」 but shorter and more common; it can also mean one copy of a book.
• Synonym一端いったんNeutralWritten/formal prose. Means one end or a small portion, as in 「責任の一端」; leans toward a small part of something.
• SynonymパートNeutralLoanword for a part or part-time work, as in 「パートで働く」; in speech it mostly means a part-time job.
• SynonymセクションNeutralLoanword for a department or a passage; leans toward sections of an organization or of a piece of writing.
• Synonym部分ぶぶんNeutralThe most common word for a part; 「一部分」 stresses one part of a whole and can imply that it is only a small amount.
• SynonymポーションNeutralLoanword for a single serving or dose; leans toward food portions or the potions of video games.
• Related部門ぶもんNeutralWritten/formal prose. A department or category; leans toward divisions of a field or domain.
• Related半分はんぶんNeutralMeans half; leans toward exactly one half of something, not just any part.
• Related要素ようそNeutralWritten/formal prose. A constituent element, as in 「重要な要素」; leans toward the factors something is made of.
• Related成分せいぶんNeutralWritten/formal prose. An ingredient, as in 「主成分」; leans toward the chemical makeup of substances.
• Related半ばなかばNeutralWritten/formal prose. Half or midway, as in 「月の半ば」; leans toward the middle of a period or process.
• Related区分くぶんNeutralWritten/formal prose. A block or category produced by dividing; leans toward the act of dividing itself.
• Related部署ぶしょNeutralThe department you belong to; leans toward one's post or assigned place of work.
• Related局所きょくしょNeutralWritten/formal prose. A limited local area, as in 「局所麻酔」 or 「局所的な豪雨」; mostly seen in technical language.
• Related局部きょくぶNeutralA local part, as in 「局部的な問題」; it can also mean the private parts, so watch the context.
• Related部ぶNeutralA department or part; mostly used as a suffix, as in 「一部」 or 「北部」.
• RelatedパーツNeutralLoanword for parts, as in 「車のパーツ」; leans toward mechanical components.
• RelatedポーションNeutralLoanword for a single serving or dose; leans toward food portions or the potions of video games.
• RelatedコンポーネントNeutralLoanword for a system component; leans toward IT and engineering contexts.
• RelatedセグメントNeutralLoanword for a segment, such as a market segment; leans toward marketing.
• Related構成要素こうせいようそFormalFormal. A constituent element; leans toward academic writing.
• Related構成成分こうせいせいぶんFormalFormal. A structural component; leans toward chemistry and academic writing.
• Antonym全部ぜんぶNeutralMeans all or everything; the opposite of 「一部分」.
• Antonym全体ぜんたいNeutralMeans the whole or entirety; the opposite of 「一部分」 taken as a local part.

For one part of a whole, use 「一部分」, as in 「ほんの一部分」. Say 「一部」 when you want a shorter, simpler form. Use 「パーツ」 for parts or components, 「成分」 for ingredients, and 「局部」 for a limited local area. The opposites are 「全部」 (everything) and 「全体」 (the whole).

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

1. 全体ぜんたいのなかのある部分ぶぶん。
2. 全体ぜんたいのなかのわずかな部分ぶぶん。