110 entries under adjective topic. ×

30
indestructible(strong, tough, firm, rigid)
23
tough(strong, firm, solid, stiff)
20
adamantine(strong, tough, severe, firm)
19
rock-hard(firm, rigid, unyielding, steely)
18
flinty(strong, hard, firm, solid)
18
impenetrable(firm, solid, stiff, rigid)
13
shatterproof(strong, tough)
9
infrangible(strong, tough)
9
unyielding(strong, hard, tough, severe)
8
rigid(strong, hard, severe, firm)
6
firm(strong, hard, tough, severe)
6
steely(firm, rigid, unyielding)
5
solid(strong, hard, tough, severe)
5
hard(strong, severe, firm, harsh)
5
resistant(strong, hard, tough, solid)
5
adamant(firm, rigid, unyielding, steely)
5
rocky(firm, stiff, rigid, unyielding)
5
rugged(strong, tough)
5
sturdy
5
tight(strong, hard, tough, solid)
10 years ago|18k views|share |citing 
APASmart Define. (2016). unbreakable thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/unbreakable/thesaurus/synonyms
ChicagoSmart Define. 2016. "unbreakable thesaurus" https://smartdefine.org/unbreakable/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2016, unbreakable thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/unbreakable/thesaurus/synonyms>.
MLASmart Define. "unbreakable thesaurus" 5 January 2016. Web. 23 September 2026. <https://smartdefine.org/unbreakable/thesaurus/synonyms>