tank

A "tank" is not just something from a war movie. Most often, it means a large container for holding liquid or gas, like the fuel tank in your car or a fish tank full of water. It can also mean a heavy armored military vehicle that moves across rough ground. As a verb, "to tank" often means to fail badly or to drop fast; if a movie tanks at the box office, it is a big failure, and if a stock tanks, its price falls sharply. You can also "tank up" by filling a vehicle with fuel before a trip. So this word can point to something that holds a lot, something built for battle, or a sudden collapse.

The word "tank" first referred to a large container or reservoir, and that idea still sits at the center of its most common use today. A *tank* can be any large container that holds liquid or gas. It might be the fuel tank in a car, a fish tank in a living room, a propane tank beside a grill, or a huge metal structure storing water, oil, or chemicals. "The desert community relied on a massive water tank to survive the summer heat."

In the early 20th century, the word took on another meaning: an *armored fighting vehicle*. During World War I, "tank" was used as a secret code name, and the name stayed. Today, it refers to the large military vehicle with heavy armor and powerful guns. "The tanks rolled across the open plains during the training exercise."

Beyond physical objects, "tank" is also often used as a verb. In business, entertainment, sports, or everyday talk, *to tank means to fail badly or fall sharply. A film can tank, sales can tank, and a stock price can tank after bad news. In sports, it can also mean losing on purpose in order to get some future benefit, such as a better draft pick. When followed by "up," the meaning shifts back to filling: to tank up* means to fill a vehicle with fuel or to load yourself up with food, drink, or energy before something demanding.

From a simple container to a machine of war to a vivid verb for failure, "tank" is a flexible word that carries ideas of storage, force, and sudden decline.