tank 
(tăngk)
(tăngk)n.
1.
a. A large, often metallic container for holding or storing liquids or gases.
b. The amount that this container can hold: buy a tank of gas.
2. A usually artificial pool, pond, reservoir, or cistern, especially one used to hold water for drinking or for irrigation.
3. A usually glass-walled container in which live fish, reptiles, or other animals are kept.
4. An enclosed, heavily armored combat vehicle that is armed with cannon and machine guns and moves on continuous tracks.
5. A tank top.
6. Slang A jail or jail cell.
v. tanked, tank·ing, tanks
v.tr.
To place, store, or process in a tank.
v.intr.
Phrasal Verb: Informal To suffer a sudden decline or failure: The stock market tanked yesterday.
tank up
Idiom: 1. Slang To drink to the point of intoxication.
2. To fill the tank of a motor vehicle with gasoline.
in the tank
1. In reserve: a runner who didn't have enough in the tank to hold the lead.
2. In a state of decline or failure: Stocks have been in the tank for months.
3. Enthusiastically partial; strongly favoring: a reporter accused of being in the tank for a candidate.
[Partly from an Indic source such as Gujarati ṭāṃkhī, cistern, and ṭāṃkhī,ṃ, reservoir, or Marathi ṭāṃkeṃ, cistern, reservoir (all from Prakrit ṭaṅka, ditch, reservoir, of unknown origin) and partly from Portuguese tanque, reservoir (variant of estanque, from estancar, to dam up, from Vulgar Latin *stanticāre; see STANCH1). Noun, sense 4, from the fact that in WWI the British army tried to conceal the development and transport of such armored vehicles by referring to them as water tanks in documents and communications.]
tankful′ (-fl′) n.