facultative

adjective more facultative · most facultative

1. Of or relating to faculty, especially to mental faculty.
2. Not obligate; optional, discretionary or elective. But does the penny fare end here, said Mr. Nixon, at a merely facultative stop? Surely it ends rather at the station.

   Similar: discretionary, elective, facultative, free, noncompulsory, nonmandatory, nonobligate, nonobligatory, nonrequired, nonrequisite, optional, optionary · Opposite: basic, essential, indispensable, necessar, necessary, necessitous, needed, prerequisite, required, requisite

3. That grants permission or power to do something.
4. Able to perform a particular life function, or to live generally, in more than one way. facultative feeder

   Opposite: obligate

5. of a point At which a given function is positive. For then it is seen, as before, that it is the points outside the two sheets which are facultative, and not the points between the surface and the touching plane.