Open to choice; freely chosen.
Of, or pertaining to voting or elections; involving a choice between options.
Something that is an option or may be freely chosen, especially a course of study.
Not obligate; optional, discretionary or elective.
That grants permission or power to do something.
Able to perform a particular life function, or to live generally, in more than one way.
Of or relating to faculty, especially to mental faculty.
At which a given function is positive.