ruck

1. A throng or crowd of people or things; a mass, a pack.
2. A contest in games in which the ball is thrown or bounced in the air and two players from opposing teams attempt to give their team an advantage, typically by tapping the ball to a teammate.
3. A player who competes in said contests; a ruckman or ruckwoman.
4. Any one of a ruckman, a ruck rover or a rover; a follower.
5. The situation formed when a player carrying the ball is brought to the ground and one or more members of each side are engaged above the ball, trying to win possession of it; a loose scrum.
6. The common mass of people or things; the ordinary ranks.
7. An argument or fight. (colloquial)

Plural rucks