Definition of bissextile in English:

bissextile

adjective

  • (of a year) having the extra day (29 February) of a leap year:

    ‘in a bissextile year, any fixed festival after February leaps forward’
    ‘the year 1904 was bissextile’

Origin

Late Middle English: from Latin bisextilis (annus) or bissextilis (annus) the year of the bissextus, from bissextus (from bis twice + sextus sixth), the name given to the extra day inserted every fourth year by the Julian calendar, which was originally obtained by counting 24 February (the sixth day before the beginning of March) twice.

Pronunciation

bissextile

/bɪˈsɛkstʌɪl/