Meaning of TANK in English

I. tank 1 S2 W2 /tæŋk/ BrE AmE noun [countable]

[ Date: 1600-1700 ; Language: Portuguese ; Origin: tanque 'pool' ]

1 . a large container for storing liquid or gas:

The water tank is leaking.

Somehow the chemical got from a storage tank into water supplies.

fish/marine/breeding tank (=for keeping or breeding fish in)

the plane’s fuel tank

petrol tank British English gas tank American English

2 . ( also tankful ) the amount of liquid or gas held in a tank:

We set off next day on a full tank.

tank of

a tankful of petrol

3 .

a heavy military vehicle that has a large gun and runs on two metal belts fitted over its wheels

4 . a large artificial pool for storing water

5 . in the tank American English informal failing and losing money

be/go in the tank

Sales can’t keep going up, but that doesn’t mean the industry is going in the tank.

⇨ ↑ think tank , ↑ septic tank , ↑ drunk tank

II. tank 2 BrE AmE verb

1 . [intransitive] to decrease quickly or be very unsuccessful:

Not long after the chairman resigned, shares in the company tanked.

2 . [intransitive] British English informal to travel very fast in a car or vehicle

3 . [intransitive] informal to fail badly and be very unsuccessful SYN flop :

His last film tanked in the States, but did well in the UK.

4 . ( also tank it ) [transitive] to deliberately lose a sports game that you could have won

tank up phrasal verb

especially American English to put petrol in your car so that the tank is full SYN fill up

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.