1. an exclamation used to express approval, encouragement, or praise for someone's achievement or effort
Usage: informal; chiefly North American; often used in sports or competitive contexts

Examples

• Attaboy! You scored the winning goal!
• She finished her first marathon. Attaboy!
• Attaboy, you nailed that presentation.
• The coach shouted 'Attaboy!' when the player made the catch.
• You finally fixed the car yourself? Attaboy!