prob·lem 
(prŏbləm)
(prŏbləm)n.
1. A question to be considered, solved, or answered: math problems.
2.
a. A situation, matter, or person that is hard to deal with or understand: was having problems breathing; considered the main problem to be his boss. See Usage Note at dilemma.
b. A personal matter that causes one difficulty or needs to be dealt with: felt her tyrannical boss had deep-seated problems.
3. A misgiving, objection, or complaint: I have a problem with his cynicism.
adj.
Idiom: 1. Difficult to deal with or control: a problem child.
2. Dealing with a moral or social problem: a problem play.
no problem
1. Used to express confirmation of or compliance with a request.
2. Used to acknowledge an expression of gratitude.
[Middle English probleme, from Old French, from Latin problēma, problēmat-, from Greek, from proballein, to throw before, put forward : pro-, before; see PRO-2 + ballein, blē-, to throw; see gwelə- in the Appendix of Indo-European roots.]