"talk artlessly and childishly," 1530s, a frequentative (or diminutive) of prate (q.v.); also see -el (2) and (3). Related: Prattled; prattling. The noun, "inconsequential or childish talk," is attested from 1550s.
Prattle is generally harmless, if not pleasant, as the prattle of a child, or of a simple-minded person ; prating now generally suggests the idea of boasting or talking above one's knowledge ; chat is easy conversation upon light and agreeable subjects ... ; chatter is incessant or abundant talk, seeming rather foolish and sounding pretty much alike ; babble or babbling is talk that is foolish to inaneness, as that of the drunkard (Prov. xxiii. 29) .... [Century Dictionary, 1895]