1. To completely fail or to suffer a sudden decline or failure: Today several trading stocks tanked.

The movie tanked over the weekend even though it was supposed to be so great.

2. To make no effort to win a contest or to deliberately lose a game, match, etc.; such as, a tennis match, a basketball game, a football game, etc.: There are those who say the team deliberately tanked the game.

Referring to getting very drunk: Joe got tanked at the party.

Andy was tanked up on strong cider and, as a result, he was looking for a fight in the London bar.