Synonyms|222Antonyms|126|Broader|3Narrower|0Related|351
11
compulsory(adjective, forced, binding)
9
required(verb, adjective, voluntary, forced)
5
forced
5
indispensable
5
necessary(adjective, inevitable)
4
obligatory(adjective, essential, required)
4
mandatory(adjective, necessary, required)
3
automatic
3
essential
3
requisite
2
prerequisite(adjective, secondary, necessary)
2
basic
2
imperative(adjective, necessary)
2
inevitable
2
involuntary
2
needed
2
nonelective
2
unavoidable(adjective, uncertain)
1
book
1
imposed
<12345…7>
For more, visit Optional on Power Thesaurus
11 years ago|2.1k views|share |citing 
APASmart Define. (2015). optional thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/optional/thesaurus/antonyms
ChicagoSmart Define. 2015. "optional thesaurus" https://smartdefine.org/optional/thesaurus/antonyms (accessed September 22, 2026).
HarvardSmart Define 2015, optional thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/optional/thesaurus/antonyms>.
MLASmart Define. "optional thesaurus" 14 April 2015. Web. 22 September 2026. <https://smartdefine.org/optional/thesaurus/antonyms>