"to talk noisily, rapidly, and incoherently," 1570s, frequentative of gab (v.), or else imitative. Related: Gabbled; gabbling.
gabble (n.)
"senseless, loud, rapid talk; animal noise," c. 1600, from gabble (v.).
*g(a)lag-
G.A.R.
G.I.
gab
gabardine
gabble
gabbro
gabby
Gabe
gaberdine
gabfest