Proto-Baltic: *ber̂ǯ-a- (1) c., *ber̂ǯ-ā̂ (1) f., *berǯ-iā̃ (1) f., *bir̃ǯ-iā̃ f., *bir̃ǯ-ia- c., *bir̂ǯ-tw-ā̂ (1), *ber̃ǯ-l-ia-, *bir̃ǯ-l-ia- c.
Meaning: birch
Lithuanian: béržas 3 < 1 `Birke'; bìržē, bìrži-s, bìržtva `Birkenhain', ber̃žli-s, bir̃žli-s `herabhängender, langer Birkenzweig'
Lettish: bę̃rzs, bęr̂zs2, bę̃rza, bẽrze `Birke', bir̃zs (gen.-s), bir̂ze2, birzis `Birkenhain, Birkengehege, Hain, Laubwäldchen überhaupt'
Old Prussian: berse `Birke' V. 600
