a thorny question/problem/issue etcCOMPLICATEDa question etc that is complicated and difficult 棘手的问题 the thorny question of immigration policy 移民政策这个棘手的问题
a thorny question/problem/issue etc• Melding the top managements also would be a thorny issue.• None of these struck me as particularly penetrating answers to a thorny problem.• In addition, sending encrypted data over international boundaries represents a thorny issue: it is still illegal in some countries.
→ a thorny question/problem/issue etc at thorny(1)