Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio.
a laborer employed in underground or underwater construction projects, working under compressed air, as in a caisson or tunnel
Used by arrangement with John Wiley & Sons, Inc.
The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
A laborer who works inside a caisson, as in the construction of underwater tunnels.