- LEAPYEAR
- 2020, for one
- 1776 or 1984
- 2004, for one
- 2008, e.g.
- 2016 is the next one
- 2008 is one
- Calendar phenomenon
- 1984, e.g.
- 2012 is the next one
- When presidential elections occur
- 2012, e.g.
- We're in one now
- 2008 or 2012
- Period with a February 29th
- 2000, e.g.
- 1956.
- 2000, for instance.
- 1960.
- Calendar term.
- Bissextile.
- 1800 or 1900.
- 1968, for one.
- Flying time?
- 1968
- Spinsters' time
- 1980 or 1984
- Quadrennial occurrence
- What 1988 was
- 2000, for one
- 2012, for one
- 2020, e.g.
- Summer Olympics usually take place in one
- Three-hundred-and-sixty-six-day period
- Calendar innovation introduced by Julius Caesar
- 1996 and 2000 occurrence
- 2004 occurrence
- 2004, e.g.
- 2004, but not 2003
- 366 days
- 1776 or 2000
