| obdurate(adjective, hard, tough, severe, rough) |
| permanent(adjective, strain, firmness, labour, hardiness) |
| stationary(adjective, strain, firmness, labour, hardiness) |
| withstanding(adjective, strong, strain, firmness, tight) |
| unrelenting(adjective, tough, severe, firm, harsh) |
| immovable(adjective, determined, resolute, rigid, obstinate) |
| fixed(adjective, set, hard, secure, rough) |
| relentless(adjective, tough, severe, firm, harsh) |
| obstinate(adjective, hard, tough, rough, firm) |
| formal(adjective, characteristic, tough, correct, severe) |
| insistent(adjective, determined, resolute, obstinate, uncompromising) |
| set(adjective, hard, secure, tough, severe) |
| unshakable(adjective, determined, resolute, obstinate, uncompromising) |
| stilted(adjective, characteristic, correct, unusual, counterfeit) |
| tough(adjective, strong, hard, severe, rough) |
| adamant(adjective, hard, rough, firm, harsh) |
| tense(adjective, hard, firm, property, rigid) |
| prim(adjective, characteristic, hard, correct, proper) |
| severe(adjective, hard, tough, rough, firm) |
| ceremonious(adjective, characteristic, correct, cold, modest) |