Word of the Day:

1 : to insert (something, such as a day) in a calendar

2 : to insert between or among existing elements or layers

"The fossiliferous deposits … consist of pale pinkish-orange brown clays, brownish grey siltstones and shale, and greenish grey fine to medium grained sandstones intercalated with dark grey conglomerates…." — M. A. Khan, et al., The Journal of Animal and Plant Sciences, 31 Dec. 2011

"In order for a lunar calendar to keep up with the solar year and the seasons, it is necessary to intercalate a 13th lunar month every two or three years." — Sacha Stern, Calendars in Antiquity: Empires, States, and Societies, 2012

Intercalate was formed from the Latin prefix inter-, meaning "between" or "among," and the Latin verb calāre, meaning "to proclaim" or "to announce." It was originally associated with proclaiming the addition of a day or month in a calendar. An instance of intercalation occurred in the earliest versions of the Roman calendar, which originally consisted of 304 days and 10 months and was determined by the lunar cycle (the remaining 61.25 days of winter were apparently ignored). According to some Roman legends, it was Numa Pompilius, the second king of Rome, who intercalated the months January and February. Eventually, the word's use broadened to include other instances of introducing new elements or layers into a preexisting system.