1. painful; difficult; tough; hard
息が苦しい気がしました。I felt like I was having trouble breathing.
2. distressing; (psychologically) difficult; stressful; awkward (e.g. position)
許しますから、そんな苦しそうな顔しないでください！I forgive you, so please don't make such a distressed face!
3. straitened (circumstances); tight (financial situation); needy; struggling
4. strained (interpretation, explanation, etc.); lame (e.g. excuse); forced (e.g. smile); far-fetched
その言い訳は苦しいです。That excuse is far-fetched.
5. hard to do; unpleasant
after -masu stem of verb; often ぐるしい