To Maintain

1. (obsolete, transitive) To support(someone), to back up or assist (someone) in an action. [14^th-19th^c.]
2. To keep up; to preserve; to uphold (a state, condition etc.). [from 14^thc.]
3. To declare or affirm (a clause) to be true; to assert. [from 15^thc.]

Antonyms

• (to keep up): abandon