RhymeZone: facultative definitions

Definitions of facultative:

adjective: granting a privilege or permission or power to do or not do something
Example: "A facultative enactment"
adjective: able to exist under more than one set of conditions
Example: "A facultative parasite can exist as a parasite or a saprophyte"
adjective: of or relating to the mental faculties
adjective: not compulsory
Example: "Facultative courses in the sciences"