a determination to succeed despite being in a difficult or impossible situation, which many people think is a typical British quality. The expression comes from the attitude shown by British people who went to Dunkirk in France in small boats to help to bring back British soldiers in World War II.
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.
Dictionary pictures of the day
Do you know what each of these is called?
Click on any of the pictures above to find out what it is called.