From Longman Dictionary of Contemporary Englishchatterboxchat‧ter‧box /ˈtʃætəbɒks $ -tərbɑːks/ noun [countable] informalTALK TO somebody someone, especially a child, who talks too much
Examples from the Corpus
chatterbox• Rain was thinking that Barbara Coleman was not only a chatterbox but inclined to be dramatic, too.• He is undoubtedly the biggest chatterbox among the Cowboys and Steelers.• Cathy's a real chatterbox - she's very friendly, but all that talking can wear you out.• London's chatterbox circles are a-buzz these days with the names of famous personalities who are supposed to have Aids.• This is the chatterbox - out-talk it!• Soon, however, she confessed to finding Mrs Tillotson a fusspot and Alice a tiresome chatterbox. 