| tireless(adjective, strong, continue, firm, difficult) |
| unflagging(adjective, strong, tough, continue, fit) |
| persistent(adjective, strong, firm, determined, steady) |
| untiring(adjective, strong, continue, lively, determined) |
| persevering(adjective, strong, firm, difficult, determined) |
| dogged(adjective, strong, firm, determined, steady) |
| steadfast(adjective, resolute, persevering, tenacious, untiring) |
| determined(adjective, strong, firm, steady, resolute) |
| diligent(adjective, activity, resolute, persevering, tenacious) |
| energetic(adjective, determined, active, full, forceful) |
| unfaltering(adjective, strong, firm, determined, steady) |
| unwavering(adjective, set, strong, firm, determined) |
| resolute(adjective, set, strong, firm, determined) |
| sedulous(adjective, activity, untiring) |
| assiduous(adjective, activity, untiring) |
| tenacious(adjective, strong, tough, fit, firm) |
| unwearying(adjective, untiring) |
| unfailing(adjective, set, strong, continue, firm) |
| inexhaustible(adjective, strong, continue, firm, energetic) |
| unwearied(adjective, activity, strong, continue, firm) |