合同|ごうどうgoudou[0]heiban (flat)

1. noun, suru verb, transitive verb, intransitive verbcombination; union; joining; incorporation; amalgamation; merger; fusion
2. no-adjectivecombined; joint; united; shared
3. no-adjective, mathcongruence

• Synonym合併がっぺいNeutralFor companies or municipalities merging into a single organization, as in 「企業合併」. 「合同」 is parties acting jointly; they need not become one body.
• Synonym合体がったいNeutralTwo things fusing into one body. Common in casual speech and anime/manga, unlike the more formal 「合同」.
• Synonym連合れんごうWrittenMultiple groups forming an alliance while keeping their independence, as in 「国際連合」. Written-style; 「合同」 just has parties acting together.
• Synonym結合けつごうNeutralBonding or joining, often in chemistry or technology, as in 「分子の結合」. 「合同」 covers parties joining or acting jointly.
• Synonym統合とうごうWrittenIntegrating several things into one, as in 「学校の統合」; often administrative. Written-style compared with 「合同」.
• Synonym結びつけるむすびつけるNeutralTying things together or linking them in association; stresses the connection made. 「合同」 is about joint union or action.
• Synonym融合ゆうごうNeutralDifferent things blending into one, as in 「文化の融合」; stresses the mingling of distinct elements. 「合同」 is joint union or action.
• Synonym合流ごうりゅうNeutralRivers, people or groups converging into one, as in 「途中で合流する」. 「合同」 is broader joint union or action.
• Synonym合成ごうせいNeutralSynthesizing or compositing, often in chemistry or images, as in 「合成写真」. 「合同」 is joint union or action.
• Synonym配合はいごうNeutralMixing or blending ingredients in set proportions, as in 「成分の配合」. 「合同」 is joint union or action.
• Synonym複合ふくごうWrittenSeveral kinds combined into one, as in 「複合施設」; stresses multiplicity. Written-style, unlike 「合同」.
• Synonym併合へいごうWrittenAnnexing or absorbing into one, as in 「領土併合」; often carries a coercive nuance. Written-style compared with 「合同」.
• Synonym合わさるあわさるNeutralIntransitive: things coming together or fitting snugly, as in 「手のひらが合わさる」. 「合同」 is joint union or action.
• Synonym一体化いったいかWrittenBecoming one integrated whole, as in 「経済の一体化」; stresses the process of integration. Written-style, unlike 「合同」.
• Synonym合するがっするWrittenWritten-style verb for merging or coming together; rare in modern usage. 「合同」 is the everyday noun for joint action.
• Synonym一緒になるいっしょになるCasualColloquial: things coming together, or a euphemism for getting married. 「合同」 is more formal, for parties joining or acting jointly.
• Synonym合一ごういつWrittenWritten-style word for becoming one, as in 「知行合一」. 「合同」 is the ordinary term for joint union or action.
• Related組み合わせるくみあわせるNeutralCombining or pairing things up, or matching opponents in a contest; stresses the pairing. 「合同」 is joint union or action.
• Related合わすあわすCasualColloquial form of 「合わせる」: aligning or joining things together. 「合同」 is a noun for parties joining or acting jointly.
• Related共同きょうどうNeutralDoing or owning something jointly, as in 「共同研究」; the stress is on acting together, not on merging.
• Related合わせるあわせるNeutralJoining or matching things; very wide in use, as in 「手を合わせる」. 「合同」 is a noun for joint union or action.
• Related統一とういつNeutralUnifying into one consistent whole, as in 「国家統一」 or 「意見を統一する」. 「合同」 is joint union or action.
• Related合すがっすCasual「合す」 is another writing of 「合わす」: matching rhythm or speed, as in 「呼吸を合わす」. 「合同」 is about groups uniting.
• Related組み合わすくみあわすCasualColloquial variant of 「組み合わせる」, stressing pairing and combining. 「合同」 is parties joining or acting jointly.
• Antonym分離ぶんりNeutralAntonym: separating things, as in 「政教分離」; the opposite of joining together as 「合同」 does.
• Antonym分割ぶんかつNeutralAntonym: dividing into parts; the opposite of becoming one as 「合同」 suggests.

Use 「合同」 for several parties joining together or acting jointly, as in 「合同練習」 and 「合同会議」. For merging into one organization pick 「合併」 or 「統合」; for an alliance of independent groups, 「連合」; for simply doing something together, 「共同」; for blending into one, 「融合」. To say things come apart, use 「分離」.

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

1. 二ふたつ以上いじょうのものが一ひとつに纏まとまること。
2. 二ふたつの図形ずけいの関係かんけいにおいて、形状けいじょうが相似そうじであり、かつ面積めんせきが同一どういつであること。
3. 二ふたつの整数せいすうの間あいだに成り立なりたつ関係かんけい。整数せいすうa, bの差さがある整数せいすうnで割り切わりきれるとき、aとbはnを法ほうとして合同ごうどうという。これは、「a-bがnの倍数ばいすうである」「aとbをそれぞれnで割わった余あまりは等ひとしい」ということと同値どうちである。
4. 二ふたつ以上いじょうのものが一ひとつに纏まとまる。