| adamantine(adjective, strong, hard, tough, severe) |
| constant(adjective, good, strong, flat, firm) |
| hard-nosed(adjective, resolute, impulsive, rigid, obstinate) |
| indomitable(adjective, strong, hard, tough, firm) |
| pertinacious(adjective, strong, tough, firm, deliberate) |
| unshakeable(adjective, resolute, uncompromising) |
| positive(adjective, clear, strong, certain, resolute) |
| set in stone(expression, adjective, idiom, firm, solid) |
| strong-willed(adjective, strong, tough, firm, intense) |
| tough(adjective, clear, strong, hard, severe) |
| unflagging(adjective, strong, firm, solid, steady) |
| brave(adjective, clear, tough, severe, firm) |
| earnest(adjective, set, severe, total, sensible) |
| intent(adjective, set, strong, severe, flat) |
| single-minded(adjective, firm, sensible, harsh, solid) |
| sure(adjective, good, clear, strong, tough) |
| unswayable(adjective, hard, firm, resolute, obstinate) |
| confirmed(verb, adjective, usual, regular, persistent) |
| decisive(adjective, good, set, strong, firm) |
| dedicated(adjective, set, clear, strong, tough) |