Grease Someone's Palm Meaning

Example : 1891, Arthur Quiller-Couch, The Blue Pavilions, ch. 11:  I was never guilty of disloyalty to King Lewis, but I killed my wife's mother, pardieu!—which the judge seemed to think almost as vile, till I sent a friend to grease his palm with the last sou of my patrimony.2008, Tim Reynolds, "Traveller's tale," Sydney Morning Herald (Australia), 9 Aug. (retrieved 8 Apr. 2009):  We arrived at Almaty Airport, and from the moment the customs officer made it obvious in his fractured English that our entrance would be made easier if we greased his palm, we realised that all our Anglo-Saxon assumptions about how societies are run were not very relevant here.