adjective. having a day or month inserted to make the calendar year correspond to the solar year: "Feb. 29 is an intercalary day".
1. Adjective In John Steinbeck’s “The Grapes of Wrath,” nearly every other chapter is an intercalary chapter. 2. Noun, singular or mass Every four years there is a leap year, when one extra day, called an intercalary, is added.
