What is "bakriyyah"

Bakriyya or Bakrism ( Arabic: البكرية al-bakriyya, adjective form Bakri) is an Islamic term which had been used historically by Shia clerics to refer to the followers of Abu Bakr, and it is still used by many Shia to refer to the Sunnis.

Among those who used the term were Ibn Babawayh, Al-Shaykh Al-Mufid, Shaykh Tusi, and many others. It was also used by some non-Shias such as the Sunni Egyptian writer Mahmood Abu Riyya, and Izz al-Din ibn Hibatullah ibn Abi l-Hadid.