The Haab is the 365-day year that forms part of the Mayan calendar. It consists of 18 months, each of 20 days. The five extra days are called the uayeb, and were considered unlucky. There is no compensation for the quarter-day error, though they knew about it. The names of the months are:

  1. Pop (mat)
  2. Uo
  3. Sip
  4. Sotz' (bat)
  5. Tzek
  6. Xul (dog)
  7. Yaxk'in (new sun)
  8. Mol (water)
  9. Ch'en (black)
  10. Yax (green)
  11. Sak (white)
  12. Keh (red)
  13. Mak
  14. K'ank'in
  15. Muwan (owl)
  16. Pax
  17. K'ayab (turtle)
  18. Kumk'u

Days of the month are named in the way the European calendar does, with a number, so they went Pop 1, Pop 2, up to Pop 18, then Uo 1, and so on. This requires comment because the other Mayan year, the 260-day Tzolkin calendar, uses a different name/number system.

Every 18 890 days, or about 52 years, the two cycles realigned, so that the haab day Pop 1 would once more coincide with the tzolkin day Imix 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.