A contrivance or arrangement serving as a fulcrum for an
   oar in rowing. It consists sometimes of a notch in the gunwale of a
   boat, sometimes of a pair of pins between which the oar rests on the
   edge of the gunwale, sometimes of a single pin passing through the oar,
   or of a metal fork or stirrup pivoted in the gunwale and suporting the
   oar.