"To join the demonstration" means to participate in a protest or gather with a group of people who are expressing their opinion or advocating for a cause. Full definition
Charles Goodman, a 15 - year - old student and survivor of the Parkland shooting, cited his experience and his faith as reasons for joining the demonstration in Washington D.C. (relevantmagazine.com)
The family of terminally ill baby Charlie Gard are expected to join a demonstration outside Great Ormond... More (premierchristianity.com)