the earliest known name of the river is "euros" ("εύρος", alcman, 7th–6th century bc). indo-european "*ewru" and ancient greek "εύρύs" meant "wide". the indo-european "wr" sound shifted in thracian to "br", creating the thracian name "ebros". thereafter, the river began to be known as "hebros" in greek and latin. rather than an origin as "wide river", an alternative hypothesis is that hebros meant "goat" in thracian.