| cantankerous(adjective, tough, difficult, wild, awkward) |
| certain(adjective, firm, determined, usual, regular) |
| concluded(adjective, firm, determined, usual, regular) |
| confirmed(adjective, firm, determined, usual, regular) |
| contrary(adjective, tough, difficult, wild, determined) |
| crisp(adjective, tough, firm, fixed, distant) |
| customary(adjective, firm, determined, usual, regular) |
| decided(adjective, firm, determined, usual, regular) |
| decisive(adjective, firm, determined, usual, regular) |
| definite(adjective, severe, harsh, solid, determined) |
| determined(adjective, severe, harsh, usual, regular) |
| difficult(adjective, tough, wild, awkward, obstinate) |
| distant(adjective, tough, firm, fixed, rigid) |
| do or die(expression, adjective, idiom, tough, firm) |
| dogged(adjective, cruel, determined, fixed, pitiless) |
| dogmatic(adjective, determined, fixed, rigid, inflexible) |
| dug in(expression, adjective, secure, tough, firm) |
| enclosed(adjective, restrained, deep, absorbed, engaged) |
| entrenched(adjective, firm, determined, usual, regular) |
| firm(adjective, secure, tough, severe, determined) |