| difficult task |
| fatigue(noun, trouble, worry, difficulty, lack) |
| fatiguing(adjective, tough, rough, difficult, heavy) |
| formidable(adjective, tough, rough, difficult, heavy) |
| grief(noun, trouble, worry, difficulty, lack) |
| grievance(noun, trouble, worry, difficulty, lack) |
| grinding(adjective, tough, rough, difficult, heavy) |
| hairy(adjective, tough, rough, difficult, heavy) |
| hard knocks(noun, expression, trouble, difficulty, lack) |
| hardship(noun, burden, lack, adversity, privation) |
| hazard(noun, trouble, worry, difficulty, lack) |
| herculean(adjective, tough, rough, difficult, heavy) |
| intricate(adjective, tough, rough, difficult, heavy) |
| involved(adjective, tough, rough, difficult, heavy) |
| irksome(adjective, tough, rough, difficult, heavy) |
| knotty(adjective, tough, rough, difficult, heavy) |
| labor(noun, trouble, worry, difficulty, lack) |
| labored(adjective, tough, rough, difficult, heavy) |
| laborious(adjective, tough, rough, difficult, heavy) |
| mean(adjective, tough, rough, difficult, heavy) |