- 苦労【くろう】 - trouble, hardship, difficulty, labour, labor, toil, pains, anxiety, worry, concern, cares 
- 苦手【にがて】 - poor (at), weak (in), not very good (at), not one's cup of tea, not one's favorite 
- 苦しい【くるしい】 - painful, difficult, tough, hard, distressing, (psychologically) difficult, stressful, awkward (e.g. position), straitened (circumstances), tight (financial situation), needy, struggling, strained (interpretation, explanation, etc.), lame (e.g. excuse), forced (e.g. smile), far-fetched, hard to do, unpleasant 
- 苦しむ【くるしむ】 - to suffer, to groan, to be worried 
- 苦しみ【くるしみ】 - pain, anguish, distress, suffering, hardship 
- 苦しめる【くるしめる】 - to torment, to pain, to inflict (physical) pain, to hurt, to harass, to cause (emotional) pain, to afflict, to distress, to bother, to trouble, to stump, to baffle 
- 苦痛【くつう】 - pain, agony, suffering, distress, torment 
- ご苦労【ごくろう】 - trouble (I have put you through), (your) hard work, thank you (for your hard work), I appreciate your efforts 
- 苦情【くじょう】 - complaint, troubles, objection, grievance 
- 苦戦【くせん】 - hard fight, close game, struggle, tight contest 
- 苦悩【くのう】 - (mental) agony, anguish, suffering, distress 
- ご苦労さん【ごくろうさん】 - I appreciate your efforts 
- 苦い【にがい】 - bitter 
- 苦心【くしん】 - pains, hard work, effort, trouble, labour, labor 
- 苦笑い【にがわらい】 - bitter smile, wry smile, forced smile, strained laugh 
- 見苦しい【みぐるしい】 - unsightly, ugly, unseemly, indecent, deplorable, disgraceful, shameful 
- 苦笑【くしょう】 - bitter smile, wry smile, strained laugh, sarcastic laugh 
- 苦境【くきょう】 - difficult situation, adverse circumstances, predicament, trouble, dilemma, distress 
- 苦慮【くりょ】 - racking one's brains, worrying oneself, being anxious 
- 辛苦【しんく】 - hardship, toil, trouble