From PIE *bʰuH-, just one of three unrelated verbs fused into English's 'to be' — alongside *h₁es- (am/is) and *h₂wes- (was/were).
Exist; occur; having the state, quality, or condition of; used as an auxiliary to form continuous tenses and the passive voice.
From Old English 'bēon' (to be, to become, to exist), from Proto-Germanic *beuną (to be, to become), from PIE *bʰuH- (to become, to grow, to appear). This is only one of three PIE roots fused into the English verb 'to be': *bʰuH- gives 'be/been/being,' *h₁es- gives 'am/is,' and *h₂wes- gives 'was/were.' The PIE root *bʰuH- also produced Latin
English speakers unknowingly conjugate three completely different prehistoric verbs every time they use 'to be.' 'I am' and 'he is' come from PIE *h₁es- (to exist). 'Be,' 'been,' and 'being' come from PIE *bʰuH- (to grow, become). 'Was' and 'were' come from PIE *h₂wes- (to dwell). Three verbs, merged into one irregular paradigm