| crucial(adjective, significant, essential, basic, vital) |
| deferential(adjective, obedient, conscientious, well-behaved) |
| devoted(adjective, obedient, conscientious, well-behaved) |
| docile(adjective, obedient, conscientious, well-behaved) |
| duteous(adjective, obedient, conscientious, well-behaved) |
| elementary(adjective, significant, essential, basic, vital) |
| essential(adjective, significant, basic, vital, necessary) |
| faithful(adjective, obedient, conscientious, well-behaved) |
| indispensable(adjective, significant, essential, basic, vital) |
| indissoluble(adjective, necessary, required, obligatory, conclusive) |
| irrevocable(adjective, necessary, required, obligatory, conclusive) |
| loyal(adjective, obedient, well-behaved) |
| necessitous(essential, required, needed) |
| obedient(adjective, conscientious, well-behaved) |
| obligation |
| obliged |
| paramount(adjective, significant, essential, basic, vital) |
| peremptory |
| prime(adjective, significant, essential, basic, vital) |
| principal(adjective, significant, essential, basic, vital) |