50 entries under auxiliary topic. ×

19
substitute(noun, adjective, agent, representative, alternative)
16
alternate(noun, adjective, lower, copy, inferior)
12
reserve(noun, adjective, support, increase, lower)
8
alternative(noun, adjective, spare, extra, substitute)
8
replacement(noun, adjective, reserve, extra, agent)
8
spare(noun, adjective, support, reserve, extra)
7
secondary(noun, adjective, support, increase, spare)
7
supportive(adjective, informal, spare, reserve, secondary)
5
extra(noun, adjective, support, lower, copy)
5
standby(noun, adjective, increase, reserve, extra)
4
dummy(noun, extra, replacement, alternative, alternate)
3
provisional(extra, supernumerary)
2
accessory(noun, adjective, support, help, lower)
2
ancillary(adjective, support, spare, inferior, extra)
2
counterfeit(extra, supernumerary)
2
ersatz(extra, supernumerary)
2
imitation(extra, supernumerary)
2
makeshift(extra, substitute, replacement, alternative, alternate)
2
mock(extra, supernumerary)
2
stopgap(extra, substitute, replacement, alternative, alternate)
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APASmart Define. (2015). backup thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/backup/thesaurus/synonyms
ChicagoSmart Define. 2015. "backup thesaurus" https://smartdefine.org/backup/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2015, backup thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/backup/thesaurus/synonyms>.
MLASmart Define. "backup thesaurus" 10 April 2015. Web. 21 September 2026. <https://smartdefine.org/backup/thesaurus/synonyms>