blabbermouthed

blabber +‎ mouthed

blabbermouthed (comparative more blabbermouthed, superlative most blabbermouthed)

1. Talkative, especially in an indiscreet manner.
   • 1947 March 31, Kaspar Monahan, “Show Shops”, in Pittsburgh Press, retrieved 27 July 2010, page 12:

     Maybe I'll live long enough to see a newspaper reporter depicted on the screen as a gentleman, not a drunken, blabbermouthed, wise-cracking bum.

   • 2001, Will Self, How the Dead Live‎, →ISBN, page 94:

     The truth was that all this Freudian sex talk was the preview, a blabbermouthed precursor to all the feckless promiscuity that was to follow in the sixties.

• (talkative, especially in an indiscreet manner): bigmouthed, garrulous, loose-lipped, loquacious

• (antonym(s) of “talkative, especially in an indiscreet manner”): discreet, taciturn, tight-lipped

• blabbermouth