Etymology

Adjective

1. That which continues over an extended period of time, often associated with suffering ("long suffering").
2. Prolonged or slow to heal. The opposite of acute.
3. suffering from such affliction

   Chronic patients must learn to live with their condition

4. Inveterate or habitual.

   He's a chronic smoker

5. Very bad, awful.

   That concert was chronic

6. Extremely serious.

   They left him in a chronic condition

Noun

1. A chronic one
2. Marijuana, typically of high quality.
3. A condition of extended duration, either continuous or marked by frequent recurrence. Sometimes implies a condition which worsens with each recurrence, though that is not inherent in the term.