What word means a formal gathering?

The word that means a formal gathering, on the USCIS reading vocabulary list, is Assembly. An assembly is a gathering of people, typically for a common purpose, and the right to assemble is one of the five freedoms protected by the First Amendment to the Constitution: the freedoms of religion, speech, the press, assembly, and petition. The text of the First Amendment guarantees "the right of the people peaceably to assemble."

The Supreme Court has interpreted the assembly clause to protect public protests, marches, rallies, sit-ins, demonstrations, and similar collective expressions of opinion, subject to reasonable, content-neutral time, place, and manner restrictions (such as parade-permit requirements). The clause does not protect violent assemblies; the word peaceably is read as a meaningful limitation, and police may disperse assemblies that turn violent or threaten public safety.

Like the rest of the First Amendment, the assembly clause was applied to state and local governments through the Fourteenth Amendment in De Jonge v. Oregon (1937), and the closely related freedom of association was recognized in NAACP v. Alabama (1958). The right to assemble has been central to American civic life: abolitionist meetings, women's suffrage marches, the 1963 March on Washington for Jobs and Freedom (where Martin Luther King, Jr. delivered the "I Have a Dream" speech), Vietnam War protests, the modern civil rights movement, and the Tea Party and Occupy movements all exercised the right of peaceable assembly.

The word assembly is also used institutionally: many state legislatures call their lower house the General Assembly or the State Assembly, and the United Nations General Assembly is the principal deliberative body of the UN. On the reading test Assembly may appear in a sentence about the First Amendment or about civic gatherings.