Wikipedia
Twelver (, Athnā‘ashariyyah or Ithnā‘ashariyyah; , ) Shia Islam or Imamiyyah is the largest branch of Shia Islam. The term Twelver refers to its adherents' belief in twelve divinely ordained leaders, known as the Twelve Imams, and their belief that the last Imam, Muhammad al-Mahdi, lives in occultation and will reappear as the promised Mahdi.
Twelvers believe that the Twelve Imams are the spiritual and political successors to the Islamic prophet Muhammad. According to the theology of Twelvers, the Twelve Imams are exemplary human individuals who not only rule over the community in justice, but also are able to keep and interpret sharia and the esoteric meaning of the Quran. The words and deeds ( Sunnah) of Muhammad and the Imams are a guide and model for the community to follow; as a result, Muhammad and the Imams must be free from error and sin, known as Ismah or infallibility, and must be chosen by divine decree, or nass, through Muhammad.
Twelvers make majorities in Iran, Azerbaijan, Iraq, Bahrain; Lebanon; and significant minorities in Nigeria, Chad, Bangladesh, Tanzania, Kuwait, India, Pakistan, Afghanistan, Qatar, UAE, Saudi Arabia, Oman, Yemen, Egypt, and Uzbekistan.
Twelvers share many tenets of Shia with related sects, such as the belief in Imams, but the Ismaili Shias believe in a different number of Imāms and, for the most part, a different path of succession regarding the Imamate. They also differ in the role and overall definition of an Imam. Twelvers are also distinguished from Ismailis by their belief in Muhammad's status as the "Seal of the Prophets" ( Khatam an-Nabiyyin), in rejecting the possibility of abrogation of Sharia laws, and in considering both esoteric and exoteric aspects of the Quran. Alevis in Turkey and Albania and Alawis in Syria share belief in the Twelve Imams with Twelvers, but their theological doctrines are remarkably different.
Usage examples of "twelver".
The most important of these is the Twelver or Ithna-Ashari sect, which predominates not only in Iraq but in the Shia world generally.
Within Twelver Shia Islam there are two major legal schools, the Usuli and the Akhbari.
Broadly speaking, the Twelvers are considered political quietists as opposed to the Zaydis who favor political activism, and the Ismailis who are identified with esoteric and gnostic religious doctrines.
This man before him was the nominal Faqih, the font of jurisprudence of the Islamic Republic and the ultimate lawmaker, whose word could overrule the Parliament and any cleric, any lawyer, any scholar in the Twelver House.
The religious leaders of the Council, together with the Faqih, His Eminence the Ayatollah Khamenei, exercised ultimate political power in the government and ultimate spiritual power in most of the Twelver Shiite Muslim world.