WordReference Random House Unabridged Dictionary of American English © 2025
bis•sex•tile
(bī seks′til, -tīl, bi-),USA pronunciation adj.
n.
- Timecontaining or noting the extra day of leap year:The years 1980 and 1984 were both bissextile.
n.
- TimeSee leap year.
- Late Latin bi(s)sextilis (annus) leap year, equivalent. to bissext(us) bissextus + -ilis -ile
- 1585–95