RichThesaurus
nonoptional
nonoptional
synonyms
required
non-optional
mandatory
compulsory
unbewised
decretory
unoptional
binding
compulsatory
unvoluntary
involuntary
obligatory
imperative
forced
obligate
requisite
nonoptional
antonyms
optional
volitional
voluntary
optionary
facultative
noncompulsory
nonobligatory
discretionary
elective
free