Fuel source is an important term used to describe the origin of energy used to power various machines and devices. The crossword solutions for this term include PEAT (4 letters), COAL (4 letters), GASPUMP (7 letters), COALMINE (8 letters) and PEATMOSS (8 letters). PEAT and PEATMOSS are both organic materials formed from partially decomposed plant matter, which can be burned as fuel. COAL and COALMINE refer to a combustible black or brownish-black sedimentary rock composed of carbon and other elements, which is mined and used as a fuel source. GASPUMP refers to a device used to dispense gasoline, diesel, and other fuels, which is powered by electricity or gas.