乌纳（Uinal）是马雅历20金的长纪历周期，有20天。假如玛雅人的长纪历日期为12.19.13.15.12（2006年12月5日），那12.19.13.15.12之中写的15就是乌纳。

A winpoin (Mayan pronunciation: [wiˈnal]), uinal is a unit of time in the Maya Long Count calendar equal to 20 days (or k'in). It is the 4th digit on the Maya Long Count date.

For example, in the Maya Long Count date 12.19.13.15.12 (December 5, 2006), the number 15 is the winal.