Abbat (lotini abbas, yun. abba, oromi abo— padar), dar kalisoi katoliki rohbalad va piri dayr, qisman sohibvakolati rohiboni nasroni, padari ruhoni, ustod va peshvoi dindoron dar jamiyati rohibon. Salohiyati Abbat az rui nizomnomavu qavoidi dayri, ki muallifonu murattibonash Vasiliy Velikiy (asri 4) va Benedikt Nursiyskiy (okhiri asri 5 va avvali asri 6) budand, muqarrar karda shudaast. Az soli 530 ba Abbat vakolati yakumra doda meshavad. Abbat dar ierarkhiya (martaba)-i kalisoi bad az episkop joyi duyumro ishgol mekard.
Dar akhirhoi 8 — 9 dar sistemai siyosii Evropai Garbi Abbas yake az mansabhoi muhim va mufid hisob meyoft. Arbobi davlati ba rohibonu zohidon baroi har guna khizmati shoista unvoni Abbatro medodand. Bad az islohoti papai Rim Grigoriy VII (asri 11) Abbat az tobeiyati hokimiyati imperatori barovarda shud. Abbat, ki dayri katolikiro sardori mekunad, odatan, az viloyati tobe ba episkop intikhob va hamchun Abbat qiyosan nomguzori karda meshavad (lotini aiifjtgdshgj); garchande u unvoni episkopi nadoshta boshad ham, doirai huquqi vay ba salohiyati episkopi eparkhiali mutobiqat mekunad. Abbatzan dar rafti idorakunii dayri zanona hamon vazifahoro inro mekunad, lekin az huququ martabai olii muqaddasi rohibi mahrum ast.