The crossword solution for the term 'TANK FILL' is GAS, which is an abbreviation for gasoline. Gasoline is a petroleum-derived liquid mixture that is used as fuel in internal combustion engines. It is composed of hydrocarbons, additives, and other compounds, and is typically derived from crude oil. Gasoline is widely used in automobiles, motorcycles, and other vehicles, and is also used in some aircraft and boats.