Bi'ssextile. n.s. [from bis, and sextilis, Lat.] Leap year; the year in which the day, arising from six odd hours in each year, is intercalated.
The year of the sun consisteth of three hundred and sixty five days and six hours, wanting eleven minutes; which six hours omitted, will, in time, deprave the compute; and this was the occasion of bissextile, or leap year. Brown's Vulgar Errours, b. iv. c. 12.
Towards the latter end of February is the bissextile or intercalar day; called bissextile, because the sixth of the calends of March is twice repeated. Holder on Time.