Generally, a flammable liquid means a liquid which may catch fire easily.

In the USA, there is a precise definition of flammable liquid as one with a flashpoint below 100 degrees Fahrenheit. Less-flammable liquids (with a flashpoint between 100 degrees and 200 degrees Fahrenheit) are defined as combustible liquid. This definition is used by the National Fire Protection Association, The US Department of Transportation, the US Environmental Protection Agency, the US Occupational Safety and Health Administration and others. Fahrenheit is a temperature scale named after the German physicist Daniel Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... Fahrenheit is a temperature scale named after the German physicist Daniel Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... The National Fire Protection Association (NFPA) is a U.S. organization (albeit with some international members) charged with creating and maintaining minimum standards and requirements for fire prevention and suppression activities, training, and equipment, as well as other life-safety codes and standards. ... Established October 15, 1966 Activated April 1, 1967 Secretary Mary Peters Deputy Secretary Maria Cino Budget $58 billion (2004 estimate) Employees 58,622 (2004 estimate) The United States Department of Transportation (DOT) is a Cabinet department of the United States government concerned with transport. ... EPA redirects here. ... The United States Occupational Safety and Health Administration (OSHA) was created by Congress under the Occupational Safety and Health Act, signed by President Richard M. Nixon on December 29, 1970. ...

Threse categories are further subdivided, depending on the liquid's flashpoint and boiling point.

• Class IA flammable liquids have a flash point below 73 °F and a boiling point below 100 °F
• Class IB flammable liquids have a flash point below 73 °F and a boiling point greater than or equal to 100 °F
• Class IC flammable liquids have a flash point greater than or equal to 73 °F and below 100 °F

• Class II combustible liquids have a flash point greater than or equal to 100 °F and below 140 °F
• Class IIIA combustible liquids have a flash point greater than or equal to 140 °F and below 200 °F
• Class IIIB combustible liquids have a flash point greater than or equal to 200 °F