A loaded question is one that has a presupposition not already agreed upon by those involved in the current discussion. As such, it is a complex question (one that includes an assertion in addition to a question). A complex question is not fallacious if its presuppositions are accepted by all participants in the discourse. But when this is not the case, the complex question is fallacious and is called a loaded question.

The classic case is when the comedian Groucho Marx asked a man, "Yes or no, have you stopped beating your wife?" Whether the man answers yes or no, he is admitting that he has beaten his wife in the past.

References: ​Loaded Question (29 Examples)