Le-bar-ber is New Hebrew, similar to the Hebrew word “barbari” = barbaric, i.e. straight from how English has made use of the Greek.
“lebarber” does not exist (as far as I can see) in the authoritative Even-Shoshan dictionary from 1981, but is found in the popular Sapir dictionary of 2001. My guess is that this word “to speak nonsense” is taken straight from the original Greek “to babble.”
btw: Hebrew often assimilates words from foreign language (especially Aramaic) and creates neologisms in verbs using this format> le-x-a-x-e-x. E.g, to telephone: le-tal-phen. Bayit is “house”, le-va-yet” is to domesticate. to torpedo: le-tar-ped. Le-bal-bel, as in Tower of Babel, means to confuse.
Question for those who know Persian: the very common Hebrew word “balagan” (disorder, a mess) is said to come from a Persian word meaning “market” or “street theater”. Others say “temporary wooden structure for folk performances” - “balachane”. Either/both right? In Hebrew, the word has come to mean “disorder”, and then the verb: le-val-gen—to create disorder.
Hebrew has a single word for all foreign languages: “lo’azit”. Aside from the Greek “barbar”, does anyone know if other languages have a single term for all foreign languages?