A motion for more definite statement in many jurisdictions in the United States, and under United States federal law, is a means of obtaining a more detailed motion from the opposing party in a civil case before interposing a responsive pleading.
Federal civil procedure
In United States federal court jurisprudence, the motion is permitted by Rule 12(e) of The Federal Rules of Civil Procedure.
The reason for this motion is that the "responsive pleading is allowed but which is so vague or ambiguous that the party cannot reasonably prepare a response."
In the Commonwealth of Virginia, a motion seeking such relief is called a motion for a bill of particulars.