📅 To add time 📚 To insert between

to intercalate

9.9

To add an extra day or month to a calendar to keep it in line with the seasons

verb
/ˌɪntərˈkeɪleɪt/

Specialized

: intercalar

To prevent the calendar from drifting, the council decided to intercalate seven days into the schedule.

Examples

Some calendars intercalate an extra day every four years to account for the Earth's orbit.
Historically, certain cultures would intercalate a month to keep the lunar and solar years aligned.
The calendar will intercalate an extra day next year.
Why do we intercalate leap years?
The calendar needs to intercalate an extra day every four years to account for leap years.
To ensure accuracy, we must intercalate a month into the calendar every few years.
The committee decided to intercalate an additional day between July and August this year.

Surface Forms

intercalate infinitive

intercalated past

intercalated past participle

intercalating present participle

intercalates third person singular

Morphology

intercalate = inter + cal + ate

The prefix 'inter-' (between) and verb-forming '-ate' give a general sense of inserting, but the root 'cal' is not a standalone modern English base linked transparently to 'calendar', so the calendar-specific sense is not fully predictable for learners.

Etymology

Intercalate comes from Latin parts inter- 'between' and calare, a root you can see in calendar. It originally meant to put extra days 'between' others, which is why today it means to add a day or month into a calendar.