Perhaps from merging of:
Per Vasmer , Snoj : From *bľuti ( “ to surge, to gush ” ) + *-ati , from Proto-Balto-Slavic *bljauˀtei , ultimately from Proto-Indo-European *bʰlewH- . Cognate with Lithuanian bliáuti ( “ to bleat, to weep ” ) , Latvian bļaût ( “ to bleat ” ) and further akin to Ancient Greek φλύω ( phlúō , “ to boil over ” ) , Latin fluō ( “ flow ” ) . Related terms such as *blyjati , *blyvati can only descend from this source.
Per Trubačev (ESSJa): Specifically for the expressive meaning “to vomit, to puke”, possibly from an earlier *bjьvati , analogous to Proto-Slavic *pľьvati ( “ to spit ” ) < *pjьvati . Descendants without epenthetic *-ľ- are attested in dial. Bulgarian бю́вам ( bjúvam ) .
*bľьvati impf [ 1] [ 2] [ 3]
to gush , to spout (liquid, fume)
( expressive ) to vomit , to puke
Conjugation of
*bľьvati, *bľьva, *bľujetь (
impf. ,
-a/V- , s-aorist, accent paradigm c)
Verbal noun
Infinitive
Supine
L-participle
*bľьvanьje
*bľьvati
*bľьvatъ
*bľьvalъ
Participles
Tense
Past
Present
Passive
*bľьvanъ
*bľujemъ
Active
*bľьvavъ
*bľuję
Aorist
Present
Person
1st
2nd
3rd
1st
2nd
3rd
Singular
*bľьvaxъ
*bľьva
*bľьva
*bľujǫ
*bľuješi
*bľujetь
Dual
*bľьvaxově
*bľьvasta
*bľьvaste
*bľujevě
*bľujeta
*bľujete
Plural
*bľьvaxomъ
*bľьvaste
*bľьvašę
*bľujemъ
*bľujete
*bľujǫtь
Imperfect
Imperative
Person
1st
2nd
3rd
1st
2nd
3rd
Singular
*bľьvaaxъ
*bľьvaaše
*bľьvaaše
—
*bľuji
*bľuji
Dual
*bľьvaaxově
*bľьvaašeta
*bľьvaašete
*bľujivě
*bľujita
—
Plural
*bľьvaaxomъ
*bľьvaašete
*bľьvaaxǫ
*bľujimъ
*bľujite
—
Reanalysed at a later stage among some languages as:
Conjugation of
*bľьvati, *bľьva, *bľьvajetь (
impf. ,
-a- , s-aorist, accent paradigm a)
Verbal noun
Infinitive
Supine
L-participle
*bľьvanьje
*bľьvati
*bľьvatъ
*bľьvalъ
Participles
Tense
Past
Present
Passive
*bľьvanъ
*bľьvajemъ
Active
*bľьvavъ
*bľьvaję
Aorist
Present
Person
1st
2nd
3rd
1st
2nd
3rd
Singular
*bľьvaxъ
*bľьva
*bľьva
*bľьvajǫ
*bľьvaješi
*bľьvajetь
Dual
*bľьvaxově
*bľьvasta
*bľьvaste
*bľьvajevě
*bľьvajeta
*bľьvajete
Plural
*bľьvaxomъ
*bľьvaste
*bľьvašę
*bľьvajemъ
*bľьvajete
*bľьvajǫtь
Imperfect
Imperative
Person
1st
2nd
3rd
1st
2nd
3rd
Singular
*bľьvaaxъ
*bľьvaaše
*bľьvaaše
—
*bľьvaji
*bľьvaji
Dual
*bľьvaaxově
*bľьvaašeta
*bľьvaašete
*bľьvajivě
*bľьvajita
—
Plural
*bľьvaaxomъ
*bľьvaašete
*bľьvaaxǫ
*bľьvajimъ
*bľьvajite
—
East Slavic:
Old East Slavic: бльвати ( blĭvati )
Old Ruthenian:
Russian: блева́ть ( blevátʹ )
South Slavic:
West Slavic:
^ Derksen, Rick (2008 ) “*bļьvàti”, in Etymological Dictionary of the Slavic Inherited Lexicon (Leiden Indo-European Etymological Dictionary Series; 4), Leiden, Boston: Brill, →ISBN , page 46 : “v. ‘vomit’ ”
^ Olander, Thomas (2001 ) “bljujǫ bljьvati”, in Common Slavic Accentological Word List [1] , Copenhagen: Editiones Olander: “c (SA 204, 207, 236; PR 133) ”
^ Snoj, Marko (2016 ) “bljavati ”, in Slovenski etimološki slovar [Slovenian Etymology Dictionary ] (in Slovene), 3rd edition, https://fran.si : “Pslovan. *bl'ьva̋ti, sed. *bl'ȗjǫ ”
Vasmer, Max (1964–1973 ) “блева́ть ”, in Oleg Trubachyov , transl., Этимологический словарь русского языка [Etymological Dictionary of the Russian Language ] (in Russian), Moscow: Progress
Trubachyov, Oleg , editor (1975 ), “*bľьvati, *bľujǫ ”, in Этимологический словарь славянских языков [Etymological dictionary of Slavic languages ] (in Russian), numbers 2 (*bez – *bratrъ ), Moscow: Nauka, page 140
Georgiev, Vladimir I. , editor (1971 ), “бълвам, блъвна ”, in Български етимологичен речник [Bulgarian Etymological Dictionary ] (in Bulgarian), volume 1 (А – З ), Sofia: Bulgarian Academy of Sciences Pubg. House, →ISBN , page 98