oarlock

n. pivot for an oar; lock for an oar; device for holding an oar

A rowlock (British) or oarlock (US) is a device that attaches an oar to a boat. When a boat is rowed, the rowlock acts as a fulcrum, and, in doing so, the propulsive force that the rower exerts on the water with the oar is transferred to the boat by the thrust force exerted on the rowlock.On ordinary rowing craft, the rowlocks are attached to the gunwales. In the sport of rowing, the rowlocks are attached to outriggers (often just called "riggers"), which project from the boat and provide better leverage. In sport rowing, the rowlocks are normally U-shaped and attached to a vertical pin which allows the rowlock to pivot around the pin during the rowing stroke. They additionally have a locking mechanism across the top of the "U" to prevent the oar from unintentionally popping out of the rowlock.
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Noun
1. a holder attached to the gunwale of a boat that holds the oar in place and acts as a fulcrum for rowing
(synonym) peg, pin, thole, tholepin, rowlock
(hypernym) holder
(part-holonym) dinghy, dory, rowboat

(n.)
The notch, fork, or other device on the gunwale of a boat, in which the oar rests in rowing. See Rowlock.
  

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