1. the lowest possible level The morale of prison officers is at rock bottom.The president's opinion poll ratings have hit rock bottom.
2. if you are at rock bottom, you are the most unhappy you have ever been in your life I'd never felt so depressed in my life - I was at rock bottom - so I started drinking.After Carly left me I hit rock bottom.
The lowest possible level, absolute bottom, as in Wheat prices have reached rock bottom. This idiom alludes to the presence of bedrock that prevents digging farther down. [Late 1800s]