Wikipedia
Tzolk'in (, from the revised Guatemala Mayan languages Academy orthography, which is preferred by the linguists of the Summer Institute of Linguistics; formerly and commonly tzolkin) is the name bestowed by Mayanists on the 260-day Mesoamerican calendar originated by the Maya civilization of pre-Columbian Mesoamerica.
The tzolk'in, the basic cycle of the Maya calendar, is a pre-eminent component in the society and rituals of the ancient and the modern Maya. The tzolk'in is still in use by several Maya communities in the Guatemalan highlands. Its use is marginal but spreading in this region, although opposition from Evangelical Christian converts continues in some communities.
The word tzolk'in, meaning "division of days", is a western coinage in Yukatek Maya. There are various terms in actual use in the languages of Maya groups who have maintained an unbroken count for over 500 years: The K'iche' use the term Aj Ilabal Qʼij [aχ ilaɓal ʠiχ] or Rajilabal Kʼij [ɾaχ ilaɓal ʠiχ], 'the sense of the day' or 'the round of the days' and the Kaqchikel use the term Chol Qʼij [tʃol ʠiχ], 'the organization of time'. The names of this calendar as used by the pre-Columbian Maya are not widely known. The corresponding Postclassic Aztec calendar, was called tonalpohualli, in the Nahuatl language.