A math or logic error that can be detected only when the program runs. Examples of run-time errors are dividing by a variable whose value is zero or calling a DLL function that doesn't exist.
An error that occurs when code is running. A run-time error results when a statement attempts an invalid operation.
Run-time errors happen while your program is executing. Run-time errors are logic errors and therefore usually harder to track down than compile-time errors.
An error in a program that causes execution of the program to be terminated. These are caused by misuses of the language that the compiler cannot detect and so are detected only when the program is run. They might include sending messages to null, dividing integers by zero, trying to access non-existent elements of an array, etc.
An error the computer system finds in a program during run time.