Free will.
1. A will free from improper coercion or restraint. To come thus was I not constrained, but did On my free will. Shak.
2. The power asserted of moral beings of willing or choosing without the restraints of physical or absolute necessity.
Shades of meaning
Fernald lists free will only as an antonym, under predestination.
He lists it without comment; the entries above explain its neighbors.
Synonyms
none given