0 to be officially weighed before competing in a sport, especially boxing or horse racing: --
1 to become involved in an argument or discussion in a forceful way: --
Several leading architects weighed in with criticisms regarding the design of the new museum.
2 to give an opinion or enter a discussion or argument: --
The senator weighed in with a blistering attack on welfare cheats.
3 to measure how heavy someone is, esp. before a competition: --