Real Dictionary

trouble
If you have kidney trouble or back trouble, for example, there is something wrong with your kidneys or your back.
If you tell someone that it is no trouble to do something for them, you are saying politely that you can or will do it, because it is easy or convenient for you.
You can refer to problems or difficulties as trouble.
Your troubles are the things that you are worried about.
singular noun: If you say that one aspect of a situation is the trouble, you mean that it is the aspect which is causing problems or making the situation unsatisfactory.
uncountable noun: If there is trouble somewhere, especially in a public place, there is fighting or rioting there.

trouble in American English
to disturb or agitate
intransitive verb: to put oneself to inconvenience, extra effort, or the like
noun: difficulty, annoyance, or harassment
transitive verb: to disturb the mental calm and contentment of; worry; distress; agitate

trouble in British English
noun: a state or condition of mental distress or anxiety
verb: to cause trouble to; upset, pain, or worry