1. superlative form of blabby; most inclined to talk too much or reveal secrets
Usage: informal; superlative of 'blabby'

Examples

• She's the blabbiest person in the office—don't tell her anything you want to keep private.
• He was the blabbiest kid in class, always interrupting and sharing everyone's business.
• Of all my friends, she's the blabbiest when she's had a few drinks.
• The blabbiest member of the team accidentally revealed the surprise party plan.
• I wouldn't call him the blabbiest, but he does talk a lot at meetings.