Old English bēon, an irregular and defective verb, whose full conjugation derives from several originally distinct verbs. The forms am and is are from an Indo-European root shared by Latin sum and est. The forms was and were are from an Indo-European root meaning ‘remain’. The forms be and been are from an Indo-European root shared by Latin fui ‘I was’, fio ‘I become’, and Greek phuein ‘bring forth, cause to grow’. The origin of are is uncertain.