23
unnecessary(adjective, unimportant, trivial, valuable, required)
9
voluntary(adjective, unimportant, trivial)
9
inessential(noun, adjective, unimportant, trivial)
8
ancillary(adjective, extra, supplementary)
6
needless(adjective, reasonable, unimportant, trivial)
5
unimportant(adjective, important, substantial, trivial)
4
nonessential(adjective, important, unimportant, trivial, essential)
4
superfluous(adjective, reasonable)
4
surplus(adjective, extra, wanting)
4
useless(adjective, unimportant, trivial)
3
extra(adjective, common, usual, unimportant, trivial)
3
dispensable(adjective, able, necessary)
3
spare(adjective, reserve, extra, thick)
3
contingent(adjective, unimportant, trivial)
2
optional
2
gratuitous
2
avoidable
2
discretionary
2
doubtful
2
elective
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APASmart Define. (2015). necessary thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/necessary/thesaurus/antonyms
ChicagoSmart Define. 2015. "necessary thesaurus" https://smartdefine.org/necessary/thesaurus/antonyms (accessed September 21, 2026).
HarvardSmart Define 2015, necessary thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/necessary/thesaurus/antonyms>.
MLASmart Define. "necessary thesaurus" 2 November 2015. Web. 21 September 2026. <https://smartdefine.org/necessary/thesaurus/antonyms>