Definitions

1. noun

A year that is a leap year, in which an extra day is added to the month of February to keep the calendar aligned with the solar year.

“The ancient Romans celebrated the bissextus with great festivities to mark the extra day in February.”

2. adjective

Relating to or characteristic of a year that is a leap year.

“The bissextus calendar system was used by the ancient Romans to keep their calendar in sync with the solar year.”