Answer

It depends for what purpose. In the laws of disqualification from testimony, the Talmud derives that a wicked person is someone liable to lashes (or more). Someone who violated a prohibition that does not incur lashes is not disqualified from testimony as a wicked person.
A secular person is a broad label that includes many kinds of people. Someone who does not believe is not wicked, but rather coerced by his understanding. Someone who does not observe the commandments despite understanding that they are binding is wicked.