The Phrygian word ΒΡΑΤΕΡΑΙΣ
Word ΒΡΑΤΕΡΑΙΣ
b r a t e r a i s
Transliteration braterais
Meaning brother
See also Lydian: brafr- ‘a member of the commune’
Armenian: elbayr ‘brother’
Ionic Greek: φρά̄τηρ ‘brother’
Proto-Indo-European: *bʰráH₂ter- ‘brother’
Tocharian B: procer ‘brother’
Synonyms ΒΡΑΤΕΡΕ

Comments
Probably Mysian dialect of Phrygian.

See J. Pokorny Proto-Indo-European Etymological Dictionary

Other words that might be of interest
ΑΝΑΡ ‘man, husband’, ΚΝΑΙΚΑ ‘woman’, ΖΕΜΕΛΩΣ ‘man, human being’, ΠΑΤΗΡ ‘father’, ΓΕΛΑΡΟΣ ‘sister in law’, ΟΡΟΥΑΝ ‘guardian, warden, father’, ΠΕΝΘΕΡΩ ‘father in law’, ΙΑΝΑΤΕΡΑ ‘husband’s brother’s wife’, ΟΥΕΛΑ- ‘family, relatives’, ΟΡΟΥΕΝΑΝ ‘father’, ΒΟΝΟΚ- ‘woman, wife’, ΕΡΟΚΑ ‘progeny, family’, ΚΟΡΟΑΝ ‘girl’