Bissextus – A new word… February 29, 2016 / Robin Definitions for bissextus February 29th: the extra day added to the Julian calendar every fourth year (except those evenly divisible by 400) to compensate for the approximately six hours a year by which the common year of 365 days falls short of the solar year. Share this: Share on X (Opens in new window) X Share on Facebook (Opens in new window) Facebook Print (Opens in new window) Print Email a link to a friend (Opens in new window) Email More Share on Pocket (Opens in new window) Pocket Like Loading... Related