noun

• (countable) The ball used in any game called "football".
  "The player kicked the football."
• (UK, Africa, Caribbean, South Asia, uncountable) Association football, also called soccer: a game in which two teams each contend to get a round ball into the other team's goal primarily by kicking the ball.
  "Each team scored three goals when they played football."
• (US, uncountable) American football: a game played on a field 100 yards long and 53 1/3 yards wide in which two teams of 11 players attempt to get an ovoid ball to the end of each other's territory.
  "Each team scored two touchdowns when they played football."
• (Canada, uncountable) Canadian football: a game played on a field 110 yards long and 65 yards wide in which two teams of 12 players attempt to get an ovoid ball to the end of each other's territory.
  "They played football in the snow."

verb

• (intransitive, rare) To play football.
  "It was an announcement of the outbreak of what is now termed World War I. Some of us lads were footballing when we heard the news. It left us bewildered."