A "tank trailer" is a type of trailer used for transporting liquids or gases in bulk quantities. There are several synonyms for this type of trailer, including tanker trailer, liquid trailer, bulk trailer, and tanker truck trailer. These trailers typically have a cylindrical shape and are designed to hold varying amounts of fluids, from a few thousand gallons to over 10,000 gallons. Tank trailers are commonly used for transporting gasoline, diesel, water, chemicals, and other materials. They are an essential tool for businesses in the petroleum, chemical, and agricultural industries, as well as for municipalities and government agencies that need to transport liquids or gases.