| No. | Item | Definition |
|---|---|---|
| 1. | abstruse | hard to understand; obscure |
| 2. | advanced | beyond basic level; hard |
| 3. | arcane | known by few; hard to grasp |
| 4. | arduous | requiring great effort over time |
| 5. | awkward | hard to manage or handle |
| 6. | awkwardly shaped | hard to handle physically |
| 7. | backbreaking | requiring exhausting physical labor |
| 8. | baffling | extremely hard to understand |
| 9. | bewildering | very confusing and hard to follow |
| 10. | bleak | discouraging and hard to face |
| 11. | bothersome | annoying and hard to deal with |
| 12. | burdensome | difficult because it weighs heavily |
| 13. | challenging | testing ability or effort |
| 14. | complex | hard because intricately connected |
| 15. | complicated | hard because many parts are involved |
| 16. | confounding | confusing and difficult to resolve |
| 17. | confusing | hard to understand clearly |
| 18. | convoluted | complex and hard to follow |
| 19. | daunting | discouraging because very hard |
| 20. | delicate | requiring careful handling |
| 21. | demanding | requiring much effort or skill |
| 22. | dicey | uncertain, risky, and hard |
| 23. | disagreeable | unpleasant and hard to accept |
| 24. | distressing | upsetting and hard to bear |
| 25. | elusive | hard to find or achieve |
| 26. | enigmatic | mysterious and hard to understand |
| 27. | esoteric | specialized and hard to understand |
| 28. | exacting | requiring precise, careful effort |
| 29. | exhausting | very tiring to do or face |
| 30. | exigent | requiring urgent attention or effort |
| 31. | fastidious | hard to please; exacting |
| 32. | finicky | hard to please; overly particular |
| 33. | formidable | impressively hard to overcome |
| 34. | fractious | irritable and hard to control |
| 35. | frustrating | difficult and causing frustration |
| 36. | fussy | hard to satisfy or please |
| 37. | grave | serious and difficult |
| 38. | grim | harsh and hard to face |
| 39. | grueling | extremely tiring and demanding |
| 40. | hairy | dangerous, tricky, or difficult |
| 41. | hard | not easy to do or understand |
| 42. | harsh | severe and hard to endure |
| 43. | heartbreaking | emotionally very hard to bear |
| 44. | high-maintenance | needing much attention or effort |
| 45. | impenetrable | impossible or hard to understand |
| 46. | incomprehensible | impossible to understand |
| 47. | inconvenient | causing trouble or practical difficulty |
| 48. | inscrutable | hard to read or understand |
| 49. | intractable | hard to control or solve |
| 50. | intricate | complex and hard to understand |
| 51. | involved | complicated and hard to follow |
| 52. | irksome | annoying and troublesome |
| 53. | knotty | complicated and hard to solve |
| 54. | laborious | requiring long, hard work |
| 55. | maddening | extremely frustrating and difficult |
| 56. | messy | complicated and hard to resolve |
| 57. | miserable | very unpleasant and hard |
| 58. | murky | unclear and hard to understand |
| 59. | mystifying | hard to explain or understand |
| 60. | nasty | very unpleasant or hard |
| 61. | obscure | hard to understand or notice |
| 62. | obstinate | stubborn and hard to influence |
| 63. | onerous | heavy, burdensome, or hard |
| 64. | opaque | hard to understand clearly |
| 65. | oppressive | hard to bear or endure |
| 66. | perplexing | confusing and hard to understand |
| 67. | perverse | willfully contrary and difficult |
| 68. | precarious | uncertain and hard to manage |
| 69. | problematic | causing problems or difficulty |
| 70. | punishing | very harsh or demanding |
| 71. | puzzling | hard to understand or explain |
| 72. | recalcitrant | stubbornly resistant to authority |
| 73. | recondite | obscure and hard to understand |
| 74. | refractory | stubbornly hard to control |
| 75. | resistant | opposing change or control |
| 76. | rigorous | strict, thorough, and demanding |
| 77. | rough | hard, unpleasant, or demanding |
| 78. | severe | very serious or hard |
| 79. | sophisticated | complex and hard to master |
| 80. | sticky | awkward and hard to handle |
| 81. | stiff | hard, demanding, or severe |
| 82. | strenuous | requiring intense effort or energy |
| 83. | stringent | strict and hard to satisfy |
| 84. | taxing | requiring much mental or physical effort |
| 85. | technical | specialized and hard for outsiders |
| 86. | thorny | difficult and full of problems |
| 87. | tiresome | tedious and hard to tolerate |
| 88. | tough | hard to deal with or do |
| 89. | tricky | hard because of hidden complications |
| 90. | troublesome | causing difficulty or annoyance |
| 91. | trying | testing patience or endurance |
| 92. | unclear | not easy to understand |
| 93. | unforgiving | allowing little room for error |
| 94. | unintelligible | impossible to understand clearly |
| 95. | unmanageable | too difficult to control |
| 96. | unwieldy | hard to handle or control |
| 97. | unyielding | not giving way easily |
| 98. | vexing | annoying and difficult to solve |
| 99. | volatile | changeable and hard to control |
| 100. | wearisome | tiring and difficult to endure |
