A written or verbal request asking a judge to decide on a matter related to your case. Motions, once submitted, are often followed by a hearing on the motion to decide whether the action that the motion is requesting should be approved or denied.
In bankruptcy court, Motions to Re-Open a case are common when a case gets dismissed and closed for any of a variety of reasons. If you, for example, had a bankruptcy case that was dismissed due to a failure to pay your filing fee, you could submit a Motion to Re-Open asking the judge to re-open your case. Your creditors may file what's called a Motion for Relief from the Automatic Stay asking the judge to allow them to repossess your vehicle or take other collection actions against you.