What is Nine ?
Nine is (noun) number 9 She’s nine (years old) tomorrow. The shop opens at 9 o’clock. nine times out of ten very often. dressed 9/11 (noun) the events of 11 September 2001, when terrorists flew aircraft into the two towers of the World Trade Center in New York, destroying them and causing thousands of deaths 999 (noun) a telephone number to call the emergency services in Britain The firemen came quickly when we called 999. The ambulance answered the 999 call. 911 (noun) the telephone number used in the United States to call for police, fire, or ambulance emergency services
source: Easier English, Student Dictionary Upper Intermediate Level