problem (EN)
noun, adjective

noun “problem”

sg. problem, pl. problems
  1. something that needs to be solved or dealt with
    Solving the math problem took her the entire afternoon.
  2. a question that needs an answer, often used in education
    For homework, the teacher assigned ten math problems to practice our multiplication skills.
  3. (with a possessive determiner) unwillingness to accept something
    If he can't see your point of view, that's his problem, not yours.

adjective “problem”

problem, non-gradable
  1. (of a person or animal) hard to manage or control
    The problem horse refused to follow any of the trainer's commands.