verb (singular present am /am/; are /är/; is /iz/; plural present are; 1st and 3rd singular past was /wəz, wäz/; 2nd singular past and plural past were /wər/; present subjunctive be; past subjunctive were; present participle being /ˈbēiNG/; past participle been /bin/)
- see about.
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
For a discussion of whether it is correct to say that must be he at the door and it is I rather than that must be him at the door and it is me, see personal pronoun (usage).