An oarlock on a wooden boat.
oarlock 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.
a device, often -shaped, for holding an oar in place in rowing
oarlock definition by American Heritage Dictionary
A device, usually a U-shaped metal hoop on a swivel in the gunwale, used to hold an oar in place and as a fulcrum in rowing.