11
dull
8
boring
8
drab
7
dreary
7
flat
7
lustreless
6
colourless
6
tedious
6
vapid
5
dismal
5
lackluster(adjective, dull, flat, clean, plain)
5
lusterless
5
tiresome
5
uninteresting
4
bland
4
dingy
4
insipid
4
slow
3
dense
3
lifeless
11 years ago|3.6k views|share |citing 
APASmart Define. (2015). Lacklustre thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/lacklustre/thesaurus/synonyms
ChicagoSmart Define. 2015. "Lacklustre thesaurus" https://smartdefine.org/lacklustre/thesaurus/synonyms (accessed September 24, 2026).
HarvardSmart Define 2015, Lacklustre thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/lacklustre/thesaurus/synonyms>.
MLASmart Define. "Lacklustre thesaurus" 14 April 2015. Web. 24 September 2026. <https://smartdefine.org/lacklustre/thesaurus/synonyms>