Chatterbox

Noun

 * 1)  One who chats or talks to excess (especially a child).

Thesaurus
agreeable rattle, babbler, big talker, blab, blabber, blabberer, blabbermouth, blatherer, busybody, chatterer, conversationalist, gabber, gabbler, gasbag, gibble-gabbler, gossip, great talker, hot-air artist, idle chatterer, jabberer, jay, magpie, moulin a paroles, newsmonger, patterer, prater, prattler, quidnunc, rattle, sayer, scandalmonger, speaker, tabby, talker, tattletale, utterer, windbag, windjammer, word-slinger