Orthodox, Orthodoxy, or Orthodoxism may refer to:

Religion

* Orthodoxy, adherence to accepted norms, more specifically adherence to creeds, especially within Christianity and Judaism, but also less commonly in non-Abrahamic religions like Neo-paganism or Hinduism

Christian

Traditional Christian denominations

* Eastern Orthodox Church, the world's second largest Christian church, that accepts seven Ecumenical Councils *Oriental Orthodox Churches, a Christian communion that accepts three Ecumenical Councils

Modern denominations

* True Orthodox Churches, also called Old Calendarists, a movement that separated from the mainstream Eastern Orthodox Church in the 1920s over issues of ecumenism and calendar reform * Reformed Orthodoxy (16th–18th century), a systematized, institutionalized and codified Reformed theology * Neo-orthodoxy, a theological position also known as ''dialectical theology'' * Paleo-orthodoxy, (20th–21st century), a movement in the United States focusing on the consensus among the ecumenical councils and church fathers * Communion of Western Orthodox Churches a communion of Christian churches of Orthodox tradition adhering to customs of western Christianity * Lutheran orthodoxy, an era in the history of Lutheranism which began in 1580 from the writing of the ''Book of Concord'' * Orthodox Presbyterian Church, a confessional Presbyterian denomination located primarily in the northern United States

Academic term

* Proto-orthodox Christianity, a term coined by New Testament scholar Bart D. Ehrman to describe the Early Christian movement which was the precursor of Christian orthodoxy

Non-Christian

* Orthodox Judaism, a branch of Judaism **Modern Orthodox Judaism, is a movement within Orthodox Judaism **Haredi Judaism, groups within Orthodox Judaism that reject modern secular culture ***Hasidic Judaism, a sub-group within Haredi Judaism noted for its religious conservatism and, typically, social seclusion * Orthodox Islam, generally refers to Sunni Islam * Orthodox Hinduism, a term for Sanātanī * Orthodox Bahá'í Faith, a small Baha'i denomination * Kemetic Orthodoxy, an Egyptian neo-pagan religion that intends to reform and restore ancient Egyptian religion * Slavic Native Faith or Rodovery Orthodoxy, a term used by Neo-Slavic pagan religious organizations

Other uses

* Left-arm orthodox spin, a bowling technique in cricket * Orthodox (album), ''Orthodox'' (album), a 2013 album by American rock band Beware of Darkness * Orthodox (Jordan), a Jordanian basketball club * Orthodox File Managers, a user interface to work with file systems * Orthodox Marxism, the dominant form of Marxist philosophy between the death of Karl Marx and the beginning of World War I * Orthodox seed, a seed which may be preserved via drying or freezing * Orthodox stance, a way of positioning the feet and hands in combat sports