How Well Do You Know English Slang?
early 15c., "talk idly, chatter; talk ignorantly or superficially," of uncertain origin, perhaps imitative. Similar forms are found in Middle High German smetern "to chatter" and Swedish smattra "to patter, rattle," and cf. Danish snaddre "chatter, jabber," Dutch snateren, German schnattern "cackle, chatter, prattle." Related: Smattered; smattering.