submersible[səb mʉr′sə bəl]
submersible definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
that can function while submerged
a vessel designed to operate under water; esp., a submarine
submersible definition by American Heritage Dictionary
A vessel capable of operating or remaining under water.