Vagrancy was a state of poverty and homelessness. Those in such a state were referred to as vagrants, and typically had no job or regular source of income. Some governments considered vagrancy to be a crime.
Gaila was arrested on Thalos VI for vagrancy in 2374. Though he was unable to pay his fine, his cousin Quark did so in order to recruit him for a mission to rescue Ishka from the Dominion. (DS9: "The Magnificent Ferengi")