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 seagoing, self-propelled barge that rides at anchor, stands on partially submerged vertical legs on submerged pontoons, and serves as living quarters and a base of operations in offshore drilling. Also called semisubmersible rig.
- semˌi·sub·merˈsi·ble adjective