18
horizontal(adjective, calm, quiet, direct, smooth)
18
straight(adjective, adverb, calm, clear, direct)
17
categorical(adjective, total, energetic, absolute, positive)
17
room(noun, place, house, space, home)
17
tasteless(adjective, characteristic, dull, hard, weak)
16
outright(adjective, adverb, complete, total, big)
15
dry(adjective, calm, dull, hard, simple)
15
humdrum(adjective, dull, weak, simple, plain)
15
low(adjective, dull, close, weak, smooth)
14
drab(adjective, dull, hard, simple, soft)
14
flush(noun, adjective, calm, quiet, direct)
14
suite(noun, set, group, space, capacity)
14
unconditional(adjective, complete, utter, absolute, positive)
14
unimaginative(adjective, dull, simple, tough, excite)
14
unqualified(adjective, strong, complete, big, limited)
13
absolute(adjective, complete, energetic, big, limited)
13
dreary(adjective, dull, dark, gloomy, ordinary)
13
penniless(adjective, poor, low, informal, exhausted)
13
prostrate(adjective, smooth, level, down, lying)
13
spiritless(adjective, dull, weak, kind, soft)
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APASmart Define. (2016). flat thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/flat/thesaurus/synonyms
ChicagoSmart Define. 2016. "flat thesaurus" https://smartdefine.org/flat/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2016, flat thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/flat/thesaurus/synonyms>.
MLASmart Define. "flat thesaurus" 1 March 2016. Web. 20 September 2026. <https://smartdefine.org/flat/thesaurus/synonyms>