intransitive verb
1.
a. : to have oneself or one's possessions (as baggage) weighed (as before an airplane flight
b. of a boxer or wrestler : to have oneself weighed by a medical examiner on the day of a fight
c. of a jockey : to have oneself weighed with saddle and weights at the finish of a race — compare weigh out
2. : to enter as a participant, contributor, or mediator
a bystander weighed in to stop the fight
with a battle of quick wits to be fought in front of 500 people nature weighs in with an increased dose of adrenalin — D.E.Morris
transitive verb
1. : to take the weight of especially before an airplane flight or as a test of qualification before a contest (as a boxing match)
2. : to take the weight of (a jockey) after a race — compare weigh out