noun

• In Australian rules football
• (rugby union) 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.
• (colloquial) An argument or fight.
  "Your worth as a couple is not down to how passionate your rucks are—I said rucks—and how frantic the making-up sex is."

verb

• (obsolete, transitive) To act as a ruck in a stoppage in Australian rules football.
• (transitive, rugby union) To contest the possession of the ball in a ruck.

verb

• (transitive) To crease or fold.
  "Puzzle begged very hard to have the lion-skin taken off him. He said it was too hot and the way it was rucked up on his back was uncomfortable […]"
• (intransitive) To become creased or folded.
  ""Will you come over now and try on your dress?" Ally asked, looking at her with wistful admiration. "I want to be sure the sleeves don't ruck up the same as they did yesterday.""

verb

• (UK, dialect, obsolete) To cower or huddle together; to squat; to sit, as a hen on eggs.
  "Bot now thei rucken in here nest And resten as hem liketh best."