1. childish or immature in behavior or manner
Usage: chiefly Scottish and Northern English dialect
2. of, relating to, or characteristic of a child or children
Usage: chiefly Scottish and Northern English dialect

Examples

• His bairnish antics at the meeting were inappropriate for someone his age.
• The bairnish excitement of the children was contagious.
• She made a bairnish mistake that cost the team the game.
• His bairnish sense of humor amused the younger kids.
• The bairnish drawings covered the entire refrigerator.
• He displayed bairnish behavior when he didn't get his way.