Yes, tank is a Scrabble word!

Verb

1. Store in a tank by causing (something) to flow into it

2. Consume excessive amounts of alcohol

3. Treat in a tank

Noun

1. An enclosed armored military vehicle; has a cannon and moves on caterpillar treads

2. A large (usually metallic) vessel for holding gases or liquids

3. As much as a tank will hold

4. A freight car that transports liquids or gases in bulk

5. A cell for violent prisoners