query: What does a perfect season in football mean?
passage: Perfect season
A perfect season is a sports season including any requisite playoff portion, in which a team remains and finishes undefeated and untied. The feat is extremely rare at the professional level of any team sport, and has occurred more commonly at the collegiate and scholastic levels in the United States. A perfect regular season (known by other names outside the United States of America) is a season excluding any playoffs, where a team remains undefeated and untied; it is less rare than a complete perfect season but still exceptional.
passage: Double (association football)
A combination of domestic league or cup and a lesser domestic or continental trophy may be won in the same season. Examples include (this list does not include doubles achieved as part of a treble):A national team cannot usually win a FIFA World Cup and their continental championship in the same year because they are usually not held in the same year (except for the Africa Cup of Nations until 2010), but one which wins both titles consecutively could be said to have "done the double".