From Longman Dictionary of Contemporary Englishoaroar /ɔː $ ɔːr/ noun [countable] 1 
TTWa long pole with a wide flat blade at one end, used for rowing a boat → paddle2 → put/stick/get your oar in
TTWa long pole with a wide flat blade at one end, used for rowing a boat → paddle2 → put/stick/get your oar inExamples from the Corpus
oar• A piece of the boat or an oar or a white tennis shoe: Did tennis shoes float?• We embark, the ferryman hands us an oar, and the craft moves out from the dock.• Eddie also presented Margarett with an oar pin: he rowed seven on the Harvard varsity crew.• Though the wind be not favourable to you yet, ardently grasp the oars!• Alan insisted upon managing the oars, which made it even worse.• And when he took hold of the oars of a rowboat, the rowboat nearly jumped out of the water.• In the ensuing commotion lost one of the oars over board.Origin oar Old English ar 