Relating to the insertion between elements.

Occurring or existing in an intervening position.

Pertaining to intercalary periods in calendars or timekeeping.

Involving intervals added for adjustment purposes.

**Intercalary month** - An extra month added to a calendar.

**Intercalic day** - A day inserted into the calendar system.

**Intercalation period** - Time span for adding intercalic days/months.