A fire extinguisher was a hand-held piece of equipment that was used to dispersed a fire-retardant over a small fire.
In the year 2282 crewman Bates used a fire extinguisher to prevent a fire from spreading on the shuttlecraft Kepler after an escalating plasma wave blew out the power transfer conduit. (ST - Alien Spotlight comic: "Alien Spotlight: The Gorn")
In 2372 B'Elanna Torres used a fire extinguisher after the explosion of the plasma power grid console in the engineering of the USS Voyager damaged the automatic fire suppression system. (VOY comic: "The Storm")