A Quick and Simple Dictionary

ruck

1. Noun.  A throng or crowd of people or things; a mass, a pack. (defdate, from 16th c.) .
2. Noun.  (context, Australian Rules Football) Contesting a bounce or ball up; used appositionally in "ruck contest". Rucks also used collectively either of ruckmen or of ruckmen and ruck rovers, and occasionally used in place of "followers" (including rovers too). (defdate, from 19th c.) .
3. Noun.  (rugby union) The situation formed when a runner is brought to ground and one or more members of each side are engaged above the ball, trying to win possession of it; a loose scrum. (defdate, from 20th c.) .
4. Noun.  The common mass (term, of) people or things; the ordinary ranks. (defdate, from 19th c.) .
5. Verb.  (obsolete, transitive) To act as a ruckman in a stoppage in Australian Rules football.
6. Verb.  (transitive) To crease or fold.
7. Verb.  (intransitive) To become folded.
8. Noun.  A crease, a wrinkle, a pucker, as on fabric.