n.1 a pole with a blade used for rowing or steering a boat by leverage against the water.
2 a rower.
Phrases and idioms:
put one's oar in interfere, meddle. rest (US lay) on one's oars relax one's efforts.
Derivatives:
oared adj. (also in comb.). oarless adj.
Etymology: OE ar f. Gmc, perh. rel. to Gk eretmos oar