To be ready and able to function or begin an activity, pursuit, or task again, as after a period of dysfunction, disability, or disrepair. Okay! The engine had to be completely overhauled, but we're back in business now! Her business grew stagnant because of the building's poor condition, but she's back in business now that the place is all fixed up! Don't worry about the sprained ankle, you'll be back in business in no time!