Synonyms to be Greek to

babble, Aesopian language, Babel, Greek, absurdity, amphigory, argot, babblement, baffle, balderdash, bavardage, be beyond one, be indiscreet, be insane, be too deep, be unguarded, beat one, betray, betray a confidence, bibble-babble, blab, blabber, blah-blah, blather, blether, blethers, blurt, blurt out, bombast, bubble, bull, bullshit, burble, cackle, cant, caquet, caqueterie, chat, chatter, chattering, chitchat, chitter-chatter, cipher, clack, claptrap, clatter, code, cryptogram, disclose, dither, divulge, dote, double Dutch, double-talk, drivel, drool, escape one, fiddle-faddle, fiddledeedee, flummery, folderol, fudge, fustian, gab, gabble, galimatias, gammon, garble, gas, gibber, gibberish, gibble-gabble, gift of tongues, give away, glossolalia, go on, gobbledygook, gossip, guff, guggle, gurgle, gush, have a demon, haver, hocus-pocus, hot air, hubbub, humbug, idle talk, inform, inform on, jabber, jabberwocky, jargon, jaw, jumble, lap, leak, let drop, let fall, let slip, lose one, mere talk, mumbo jumbo, murmur, narrishkeit, natter, need explanation, niaiserie, noise, nonsense, nonsense talk, not make s