Synonyms|713Antonyms|152|Broader|9Narrower|8Related|663

308 entries under adjective topic. ×

3
airtight(fast, short, uncomfortable, resistant)
3
closed
3
crowded(close, set, solid, heavy)
3
dull(dark, gloomy, dense, cloudy)
3
enigmatical(solid, strange, supernatural, dense)
3
fleshy
3
indomitable
3
inflexible(set, strong, hard, tough)
3
resistant(hard, unfeeling, unsympathetic, prepared)
3
rigid(set, strong, hard, tough)
3
strong(close, set, hard, secure)
3
unconquerable
3
undecipherable
3
undiscoverable(hidden, unfathomable, incomprehensible, enigmatic)
2
accented
2
arduous
2
backbreaking
2
callous(set, hard, firm, stiff)
2
clayey
2
clouded
For more, visit Impenetrable on Power Thesaurus
11 years ago|15k views|share |citing 
APASmart Define. (2015). impenetrable thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/impenetrable/thesaurus/synonyms
ChicagoSmart Define. 2015. "impenetrable thesaurus" https://smartdefine.org/impenetrable/thesaurus/synonyms (accessed September 26, 2026).
HarvardSmart Define 2015, impenetrable thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/impenetrable/thesaurus/synonyms>.
MLASmart Define. "impenetrable thesaurus" 10 April 2015. Web. 26 September 2026. <https://smartdefine.org/impenetrable/thesaurus/synonyms>