v.1. To be weighed at an official weigh-in for an athletic competition: The boxer weighed in before the fight. The fighter weighed in at 250 pounds.
2. To weigh something officially, as for travel on an airplane: The ticket agent weighed our bags in. After the agent weighed in my suitcase, I went to the gate.
3. To join an ongoing discussion, debate, or competition: The president still hasn't weighed in on the issue. After striking out twice, the player finally weighed in with a base hit.