Synonyms of the word 
NONOBLIGATORY → NONMANDATORY - OPTIONAL
nonobligatory
- adj. not obligatory; not required; optional.
nonmandatory
- adj. Not mandatory.
optional
- adj. Not compulsory; left to personal choice; elective.
- n. Something that is not compulsory, especially part of an academic course.
- n. (programming) In the Swift programming language, a kind of variable that is assigned a specific data type…
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