大部分
だいぶぶん
daibubun
= most part; greater part; majority; for the most part
When Japanese speakers want to say that something applies to the bulk of a whole — not just loosely ‘most’ but a measurable, substantial portion — they reach for daibubun (大部分). Unlike the softer hotondo, which shades into ‘almost all,’ daibubun signals a precise, proportional majority, making it the go-to word in reports, analyses, and anywhere exactness counts.
Daibubun (大部分) refers to the greater or largest part of a whole, typically implying roughly 70–90% of something without claiming totality. It functions as both a noun (‘the majority of X’) and an adverb (‘for the most part’). Compared to hotondo (ほとんど), which implies nearness to completeness and feels more casual, daibubun carries a measured, formal tone that suits written and analytical contexts. Compared to daihan (大半), which is nearly synonymous, daibubun is slightly more common in written prose and official documents, while daihan appears more naturally in spoken Japanese.
The most common confusion is choosing between daibubun, daihan (大半), and hotondo (ほとんど). Use daibubun when you want to emphasize a substantial, measurable majority in a neutral or formal register — for example in a business report or academic paper. Use daihan in the same contexts, but expect it to feel slightly more natural in conversation. Reserve hotondo for situations where the proportion is very high (approaching 100%) or the tone is casual. Note also that daibubun is most naturally followed by the particle wa (は) or no (の) — for example, daibubun wa kanryō shita (大部分は完了した) or sakuhin no daibubun (作品の大部分).
The word combines three kanji: 大 (dai), meaning ‘large’ or ‘great,’ sets the scale; 部 (bu), meaning ‘part’ or ‘section,’ identifies a segment within a whole; and 分 (bun), meaning ‘portion’ or ‘share,’ adds the sense of a measurable division. Together, 大部分 literally constructs the idea of ‘the large sectioned-off share’ — a proportion that is definitively dominant but not the entirety.
Everyday use
今日の仕事の大部分は終わった。あとは報告書をまとめるだけだ。
Kyō no shigoto no daibubun wa owatta. Ato wa hōkokusho wo matomeru dake da.
Most of today’s work is done. All that’s left is putting together the report.
Casual / Social Media
旅行の計画の大部分が決まったよ！ホテルもフライトも予約済み。
Ryokō no keikaku no daibubun ga kimatta yo! Hoteru mo furaito mo yoyaku-zumi.
Most of the travel plans are set! The hotel and flights are already booked.
Formal / Cultural context
収集したデータの大部分は、都市部における消費行動の変化を示している。
Shūshū shita dēta no daibubun wa, toshi-bu ni okeru shōhi kōdō no henka wo shimeshite iru.
The majority of the collected data indicates a shift in consumer behavior in urban areas.
Daibubun is firmly rooted in written Japanese. You will encounter it regularly in newspaper editorials, government white papers, academic theses, and corporate earnings reports — contexts where the writer needs to assert a dominant proportion without overstating it as absolute. Its written-language character means that hearing it in casual speech can sound unexpectedly stiff, which is itself a useful signal for learners: if a word feels formal in your mouth, daibubun probably is.
Comparing daibubun with its near-synonyms reveals how Japanese calibrates scale and register simultaneously. Daibubun (大部分) and daihan (大半) both mean ‘the greater part,’ but daihan is more common in spoken contexts such as news broadcasts and conversation, while daibubun leans toward documents and prose. Daitasū (大多数) shifts meaning slightly to ‘the great majority of people or items,’ emphasizing count rather than proportion of a whole. Knowing which synonym fits requires reading the register as much as the meaning.
In business Japanese, daibubun appears frequently in progress updates and analytical summaries. Phrases like gyōmu no daibubun wa jidōka sareta (業務の大部分は自動化された, ‘the majority of operations have been automated’) are standard in project reports and investor briefings. Its formal weight makes it a reliable choice when you need to convey that something is mostly done or mostly true without the imprecision of a vaguer word — a quality that professional Japanese writing values highly.