compressed-air engine

from The Collaborative International Dictionary of English v.0.48

Compressed \Com*pressed"\, a.
   1. Pressed together; compacted; reduced in volume by
      pressure.
      [1913 Webster]

   2. (Bot.) Flattened lengthwise.
      [1913 Webster]

   {Compressed-air engine}, an engine operated by the elastic
      force of compressed air.
      [1913 Webster]