| persistent(adjective, obstinate, insistent, dogged) |
| picky(adjective, tough, severe, grim, critical) |
| toilsome(adjective, hard, tough, severe, difficult) |
| challenging(verb, adjective, hard, tough, severe) |
| requiring(verb, adjective, important, serious, critical) |
| rough(adjective, hard, tough, severe, difficult) |
| rugged(adjective, hard, tough, severe, rough) |
| austere(adjective, severe) |
| delicate(adjective, fastidious, fastidiousness) |
| discriminating(adjective, sharp, rough, unsympathetic, particular) |
| formidable(adjective, tough, severe, rough, difficult) |
| grim(adjective, tough, severe, difficult, harsh) |
| hard to please(expression, adjective, idiom, tough, rough) |
| hypercritical(adjective, severe, cross, contrary, meticulous) |
| painstaking |
| squeamish(adjective, meticulous, fussy, fastidious, exacting) |
| unsparing(adjective, tough, rough, difficult, harsh) |
| unyielding(adjective, hard, tough, easy, severe) |
| weighty(adjective, hard, severe, difficult, harsh) |
| complex(adjective, difficult, tedious, onerous, tiring) |