Drivel
Old English dreflian (in drivel (sense 2 of the verb)), of uncertain origin; perhaps related to draff.
wiktionary
From Middle English drivelen, drevelen, from Old English dreflian(“to drivel, slobber, slaver”), from Proto-Germanic *drablijaną, from Proto-Indo-European *dʰerebʰ-(“cloudy, turbid; yeast”).
Compare Old Dutch drevel(“scullion”).
Perhaps a blend of drive and dribble.
etymonline
drivel (v.)
Old English dreflian "to slaver, slobber, run at the nose," from Proto-Germanic *drab-, perhaps from a PIE *dher- (1) "to make muddy, darken." Transferred meaning "to speak nonsense" is mid-14c., driveling being characteristic of children, idiots, and dotards. Related: Driveling, drivelling.
drivel (n.)
early 14c., drevel "saliva, slaver," from drivel (v.). Meaning "senseless twaddle, idiotic speech or writing" is by 1852.