| industrious(adjective, activity, strong, difficult, energetic) |
| staunch(adjective, strong, tough, fit, firm) |
| steady(adjective, strong, firm, determined, resolute) |
| vigorous(adjective, strong, sound, tough, fit) |
| loyal(adjective, resolute) |
| stubborn(adjective, resolute, tenacious) |
| unswerving(adjective, set, strong, firm, determined) |
| constant(adjective, strong, firm, determined, steady) |
| indomitable(adjective, strong, firm, determined, steady) |
| pertinacious(adjective, strong, firm, determined, steady) |
| firm(adjective, strong, tough, fit, solid) |
| patient(noun, adjective, strong, firm, determined) |
| relentless(adjective, resolute, untiring) |
| resolved(adjective, resolute) |
| unflinching(adjective, set, strong, firm, determined) |
| unremitting(adjective, strong, firm, determined, steady) |
| painstaking(adjective, activity, untiring) |
| strenuous(adjective, strong, moving, difficult, energetic) |
| weariless(adjective, continue, tired, tireless) |
| bold(adjective, resolute, tenacious) |