As a Noun: 1. A building or a large room which is used for physical exercise and usually has equipment such as bars and ropes in it. English = gymnasium, gym. 2. Exercises which involve the lifting and moving of heavy weights. English = weight training, weight lifting. 3. A sport's competition that involves the lifting of heavy weights. English = weight lifting. 4. A person who lifts weights in sport's competitions. English = weight lifter. As a Verb or Adjective: 1. To go to the gym to do exercises. Informal idiomatic English = work out. 2. To lift weights for exercise or as part of a competition.