Definition of intercalary in US English:



  • 1(of a day or a month) inserted in the calendar to harmonize it with the solar year, e.g., February 29 in leap years.

    • ‘The intercalary month by which the Arabs adjusted the lunar months to the solar year is abolished, severing the connection between the religious rituals and the seasons.’
    • ‘In ancient Egypt, for civil purposes, a solar calendar of 365 days to the year was used in which there were 12 months of 30 days and 5 intercalary days.’
    • ‘He added two extra intercalary months apart from the one regular intercalary month to the year 46 BC.’
    • ‘In the old calendar, an intercalary month of 22 or 23 days called Mercedonius was inserted after the Festival of Terminalia in every other year or as needed.’
    • ‘Chinese mythology holds that disasters always strike in intercalary Augusts and Cheng was aware of the power of this superstition when he wrote his book.’
    1. 1.1 Of the nature of an insertion.
      ‘elaborate intercalary notes and footnotes’
  • 2Botany
    (of the meristem of a plant) located between its daughter cells, especially (in a grass) at or near the base of a leaf.

    • ‘The second intercalary meristem gives rise to the internode.’
    • ‘Leaves are formed from an intercalary meristem which is positioned within the leaf sheaths of subtending leaves.’
    • ‘Cell division occurs mainly at the intercalary meristem at the base of the internode, but also throughout the internode at early stages of internode development.’
    • ‘However, the intercalary meristem is considerably longer when considering the leaf extension zone.’
    • ‘In these stems and leaves with intercalary meristems, the upward transpiration stream clearly bypassed most of the enlarging cells.’


Early 17th century: from Latin intercalarius, from intercalare (see intercalate).