| immovable(adjective, firmness, hardness, solidity, sturdiness) |
| immutable(adjective, firmness, hardness, solidity, sturdiness) |
| implacable(adjective, firmness, hardness, solidity, sturdiness) |
| impliable(adjective, firmness, hardness, solidity, sturdiness) |
| inductile(adjective, firmness, hardness, solidity, sturdiness) |
| inextensible(adjective, firmness, hardness, solidity, sturdiness) |
| inextensile(adjective, firmness, hardness, solidity, sturdiness) |
| inextensional(adjective, firmness, hardness, solidity, sturdiness) |
| intractile(adjective, firmness, hardness, solidity, sturdiness) |
| intransigent(adjective, firmness, hardness, solidity, sturdiness) |
| irreconcilable(adjective, firmness, hardness, solidity, sturdiness) |
| irresilient(adjective, firmness, hardness, solidity, sturdiness) |
| lithic(adjective, firmness, hardness, solidity, sturdiness) |
| marblelike(adjective, firmness, hardness, solidity, sturdiness) |
| nonstretchable(adjective, firmness, hardness, solidity, sturdiness) |
| pat(adjective, firmness, hardness, solidity, sturdiness) |
| petrified(adjective, firmness, hardness, solidity, sturdiness) |
| petrogenic(adjective, firmness, hardness, solidity, sturdiness) |
| rigorous(adjective, firmness, hardness, solidity, sturdiness) |
| rock(adjective, firmness, hardness, solidity, sturdiness) |