The Tzolkin is one of two kinds of year in the Mayan calendar. The Tzolkin calendar is also called Tonalamati. The other kind of year was the 365-day Haab. The Tzolkin consisted of 260 days, roughly the gestation period of a human. Whereas mundane things like agriculture had to go by the Haab, the Tzolkin was used for ritual purposes and divination.

It did not consist of months, but of two overlapping week cycles, one of 13 days, one of 20 days. The 13-day week was specified using numbers, while the 20 days of the other week had names:

  1. Imix (waterlily)
  2. Ik' (wind)
  3. Ak'bal (night)
  4. K'an (corn)
  5. Chicchan (snake)
  6. Cimi (death)
  7. Manik (hand)
  8. Lamat (Venus)
  9. Muluc (water)
  10. Oc (dog)
  11. Chuen (frog/monkey)
  12. Eb (skull/tooth)
  13. Ben (cornstalk/reed)
  14. Ix (jaguar)
  15. Men (eagle)
  16. Cib (shell)
  17. Kaban (earth)
  18. Etz'nab (flint/knife)
  19. Cauac (storm)
  20. Ahau (lord)

(Hm, I can see how the same word can mean flint/knife, but I'm just taking frog/monkey on trust.)

Days of the year are named by a weekday name from the 20 week and a weekday number from the 13 week, so they would go Imix 1, Ik' 2, up to Ben 13, then Ix 1, Men 2. As 13 and 20 are relatively prime, this produced unique naming for each of the 260 days in the Tzolkin.

Every 18 890 days, or about 52 years, the two cycles realigned, so that the tzolkin day Imix 1 would once more coincide with the haab day Pop 1. This coincidence, called the Calendar Round, was regarded with awe and fear by all Mesoamerican cultures, and the Aztecs in particular engaged in more than usually bloody human sacrifice to ensure that the round of time continued.

The X in the names is pronounced like English SH, and the apostrophe indicates an ejective (forceful) consonant.