A motion to dismiss is when a party in a lawsuit asks the judge to dismiss claims, or even the entire case. A primary reason for a plaintiff to make a motion to dismiss is because he or she and the opposing party have reached a settlement outside of court. Defendants also can make motions to dismiss.
When defendants make a motion to dismiss, it could be on the grounds of a lack of personal jurisdiction, a lack of subject matter jurisdiction, improper venue, or a number of other reasons.
If a judge approves a motion to dismiss, then the case can be dismissed. Often, two parties in a civil suit will try to reach a settlement out of court. The reason why they do this is so that they can save time and money by preventing the issue from having to go to trial.