intercalary

Inserted in the calendar to make the calendar year correspond to the solar year. Used of a day or month.

Having such a day or month inserted. Used of a year.

Inserted between other elements or parts; interpolated.

In anatomy, additional; supernumerary; inserted between other parts, as the cartilages on the dorsal side of the vertebral column in many elasmobranchs.

In chronology, inserted in the calendar out of regular order, as an extra day or month; having an additional day or month, as one of a cycle of years.

Hence Inserted or coming between others; introduced or existing interstitially: as, intercalary beds in geology.

In biology, intermediate in character between two types, yet not representing the actual genetic passage from one form to the other; interposed or intercalated, yet not biologically transitional.

In medicine, the days intervening between the critical days or crises of a disease.

Inserted or introduced among others in the calendar; ; — now applied particularly to the odd day (Feb. 29) inserted in the calendar of leap year. See Bissextile, n.