16
informal(adjective, simple, relaxed, familiar, casual)
13
unauthorized(adjective, informal, irregular, unwarranted, illegal)
9
private(adjective, intimate, secret, personal, confidential)
8
off the record(expression, adjective, idiom, adverb, personal)
8
unceremonious(adjective, simple, plain, relaxed, straightforward)
7
casual(adjective, simple, informal, relaxed, familiar)
6
natural(adjective, simple, easy, plain, straightforward)
6
relaxed
6
unconfirmed(adjective, unauthorized)
6
unsanctioned(adjective, informal, illegal, pirate, unauthorized)
5
easy
5
irregular(adjective, wrong, improper, unwarranted, unacceptable)
5
loose(adjective, simple, easy, plain, modest)
4
illegal
4
nonofficial
4
secret(adjective, private, personal, confidential, hush-hush)
4
unauthorised
4
unconventional(adjective, simple, wrong, plain, relaxed)
4
unlawful
3
confidential(adjective, adverb, sensitive, special, intimate)
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APASmart Define. (2016). unofficial thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/unofficial/thesaurus/synonyms
ChicagoSmart Define. 2016. "unofficial thesaurus" https://smartdefine.org/unofficial/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2016, unofficial thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/unofficial/thesaurus/synonyms>.
MLASmart Define. "unofficial thesaurus" 26 February 2016. Web. 20 September 2026. <https://smartdefine.org/unofficial/thesaurus/synonyms>