| 異体同心 | being of one mind, acting in one accord, behaving in perfect harmony |
| 炭酸同化作用 | carbon dioxide assimilation |
| 賛否同票 | tie vote |
| 同委員会 | the same committee |
| 同郷人 | person from the same province, town, village, etc. |
| 同市 | same city |
| 同小 | the above-mentioned elementary school |
| 同大 | the said university |
| 同母姉 | sisters of the same mother, uterine sisters |
| 同列に論じる | to discuss in the same terms, to treat equally |
日猶同祖論 日ユ同祖論 | hypothesis that Jews and Japanese are of common ancestry |
| 和して同ぜず | harmonize but not agree (harmonise) |
| 同性愛者 | homosexual (person) |
| 同期外れ | synchronisation loss (in digital communications), synchronization loss |
| 合同コンパ | joint party (e.g. by students from several colleges), combined party, mixer, two or more groups, esp. female and male students, combining for a party |
| 共同作業 | group work |
| 共同出資 | joint investment |
| 同系色 | similar color, similar colour |
| 同国人 | fellow countryman, compatriot, person from same province |
| 同時性 | simultaneity |
| 同乗者 | fellow passenger |
| 同情票 | sympathy vote |
| 同点決勝 | play-off |
| 同和教育 | social integration education, education to eliminate discrimination (e.g. against burakumin) |
| 共同権利者 | co-creditor |
| 共同義務者 | co-debtor |
| 同軸 | coaxial (cable) |
| 同和 | burakumin, assimilation |
| 異名同音 | enharmonic |
| 貨幣同盟 | monetary union |
| 同送 | shipped together, sent at the same time |
| 同姓同名 | (having) same family and personal name |
タンパク同化ステロイド 蛋白同化ステロイド | anabolic steroid |
| 共同企業体 | joint venture, consortium, JV |
| 共同軍事演習 | joint military exercise |
| 共同持ち株会社 | joint holding company |
| 共同捜査 | joint investigation |
| 同時放送 | simulcast |
| 同点決勝戦 | tiebreaker |
| 同毒療法 | homeopathy |
| 独立国家共同体 | Commonwealth of Independent States, CIS |
| 同人誌 | publication sold directly, and not via commercial publishers, fanzine |
| ガイアナ協同共和国 | Co-operative Republic of Guyana |
| 同年代 | the same generation, coeval |
| 同区 | same ward |
| 欧州経済共同体 | European Economic Community, EEC |
| 同梱 | including something in a package |
| 同部屋 | wrestlers from the same stable |
| 公私混同 | intermingling of public policy with private interest, mixing up official business with personal affairs |
| 医食同源 | a balanced diet leads to a healthy body, healthy food both prevents and cures sickness |
| 和光同塵 | living a quiet life by effacing oneself |
| 異字同訓 | different kanji with the same Japanese reading (and usu. a similar meaning) |
| 一味同心 | (people) working together with one mind |