Look up ninth in Wiktionary, the free dictionary.
1/9 may refer to:
- 1/9 (number), a fraction (one ninth, 1⁄9)
- 1st Battalion, 9th Marines, an infantry battalion of the United States Marine Corps
- January 9 or September 1, depending on date format
- Breaker 1/9, a song by Common
- Former 1 (New York City Subway service) and 9 (New York City Subway service), which shared the same route
- U.S. Route 1/9, in New Jersey