grease gun

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A hand-powered pump used to force grease under pressure into bearings.
• noun A submachine gun.

from the GNU version of the Collaborative International Dictionary of English.

• noun A device held in the hand, having a supply of grease and attached to a reservoir of pressurized air, used to force grease between adjacent moving parts of a machine, especially in the bearings of motor vehicles.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a levered device for forcing grease into machinery.
• noun colloquial a small machine gun, particularly the .45 calibre M3 used by the US in WW2.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a hand-operated pump that resembles a revolver; forces grease into parts of a machine