Uncertain. Commonly considered a substrate word. Probably ultimately from Proto-Indo-European *h₁eh₂ter-, *eh₂ter-, *ātr- (“fire”) through some intermediate; compare Avestan 𐬁𐬙𐬀𐬭𐬱 (ātarš, “fire”), Albanian vatër (which may come ultimately from an Iranian language such as Scythian or Sarmatian). Sometimes considered to be derived or borrowed from the Albanian vatër (definite form vatra); compare also Serbo-Croatian vatra (“fire”). The relationships between the languages are unclear, and it is disputed which language borrowed from which, or if it had a common Paleo-Balkanic source. It may be that some of the Slavic cognates were borrowed from proto-Romanian or other Vlach languages, through semi-nomadic Aromanian shepherds. Another theory suggested is Byzantine Greek βάθρον (báthron).  On the basis of the characteristic of Albanian adding an initial 'v' to words of ancient origin that begin with a vowel (compare vesh from Indo-European, verbër from Latin orbus, etc.), the evidence may point more to an Albanian origin for the Romanian word, as it is the only language in the Balkan region which regularly does so.
- ^ Domosileckaja, M. V. (2002) Albansko-vostočnoromanskij sopostavitelʹnyj ponjatijnyj slovarʹ: Skotovodčeskaja leksika [Albanian – Eastern Romance Comparative Conceptual Dictionary: The Pastoral Vocabulary] (in ru), Saint Petersburg: Nauka, →ISBN, page 457
- ^ Romanian Explanatory Dictionary http://dexonline.ro/definitie/vatra
- ^ https://dexonline.ro/articol/Despre_leg%C4%83turile_rom%C3%A2nei_cu_albaneza