| strict(adjective, severe, stiff, rigid, tight) |
| strong(adjective, calm, solid, determined, steady) |
| sturdy(adjective, calm, strong, secure, firm) |
| substantial(adjective, calm, strong, secure, firm) |
| sure(adjective, calm, strong, secure, firm) |
| together(adjective, calm, strong, solid, steady) |
| tough(adjective, calm, strong, severe, solid) |
| unalterable(adjective, calm, strong, solid, steady) |
| unchangeable(adjective, calm, strong, secure, firm) |
| unchanging(adjective, firm, solid, steady, substantial) |
| unfaltering(adjective, firm, solid, determined, steady) |
| unfluctuating(adjective, calm, strong, secure, firm) |
| uniform(adjective, calm, strong, secure, firm) |
| unvarying(adjective, calm, strong, secure, firm) |
| unwavering(adjective, calm, strong, secure, firm) |
| valid(adjective, severe, stiff, rigid, tight) |
| well-built(adjective, calm, strong, solid, steady) |
| well-founded(adjective, calm, strong, solid, steady) |
| adamant |
| allegiant(adjective, firm, solid, stable, fixed) |