adjective.Talkative, especially in an indiscreet manner.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adjective.
prone to communicate confidential information
adjective.
unwisely talking too much
Word Usage
"Drew and Canning are so comfortable in front of an audience, so welcoming and encouraging and downright blabbermouthed that it’s extremely hard not to get caught up in their energy."