There are a number of synonyms for the phrase "babble on" - all of which describe speaking at length, typically in an annoying or pointless manner. Some common alternatives include talking incessantly, rambling on, going on and on, yammering, blathering, prattling and chattering. Other potential synonyms might include gibbering, jabbering, and droning. Each of these words implies a degree of aimlessness or lack of focus - suggesting that the speaker is either unable or unwilling to get to the point. Though there may be slight differences in connotation between these terms, they can generally be used interchangeably.