Rowlock \Row"lock\ (? colloq. ?), n. [For oarlock; AS. [hand]rloc, where the second part is skin to G. loch a hole, E. lock a fastening. See Oar, and Lock.]

(Naut.) 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.

Source: Webster's Revised Unabridged Dictionary (1913)