1. To unite or join with someone or something to lend support or assistance. The local community has rallied to the family after it emerged that they were unable to pay their son's medical expenses. It has been extraordinary seeing people rally to the movement with such enthusiasm.

2. To cause, compel, or incite someone to unite or join with someone or something else to lend support or assistance. In this usage, a noun or pronoun can be used between "rally" and "to." We've been canvassing neighborhoods around the county in an effort to rally people to our cause. A group of fans has been trying to rally people to the actor following the scandalous allegations against him.