noun
: an apparatus for throwing an extinguishing agent (as a jet of water) upon a fire: as
a. : a force pump with an air chamber to ensure a steady flow or an arrangement of two pumps working alternately or a direct-coupled steam engine and pump on wheels
b. : an automotive truck equipped with a motor-driven pump and hose and sometimes with a chemical fire-extinguishing unit
c. : any usually mobile apparatus (as a ladder truck) used in connection with the extinguishing of fires