1. a taunting exclamation used to express defiance, mockery, or childish teasing
Usage: informal; chiefly used by children or in playful contexts

Examples

• Nyah, you can't catch me!
• The child stuck out his tongue and said nyah to his sister.
• Nyah-nyah, I got the last cookie!
• She teased him with a playful nyah when he missed the ball.