Rally refers to a gathering, as in

• rallying (also known as rally racing), a category of motorsport
• a political rally, a demonstration, march, or parade

Rally can also refer to

• Rally, a sequence of shots in tennis
• Rally (Band), a Japanese rock supergroup
• Rally's, the name of an American fast-food restaurant chain; see Checkers Drive-In.
• A rally in certain team sports, which occurs when a team that is behind in the score makes a strong scoring effort to make up its deficit, especially late in the game.