Wayeb is the nineteenth and last period of the Haab, and it is not a full month: it counts only five days, the remainder after the eighteen twenty-day months have used up 360 days of the 365-day year. These five days, sometimes called the nameless days, were regarded as a dangerous and unlucky time, a gap between years when the ordinary order was suspended and the boundary between the human and spirit worlds grew thin. The Yucatec Maya are recorded as observing them with caution, limiting activity, avoiding risk, and performing rites to carry the community safely into the new year. Recorded here by its Yucatec name, Wayeb, this period is known from the colonial sources and the Classic inscriptions. These are the features of the Maya solar calendar, whose five closing days complete the 365 before the year begins again at Pop.
Because the Wayeb falls at the seam between one 365-day vague year and the next, and because that seam itself drifted slowly against the true solar seasons over the centuries for want of a leap-day correction, the five days did not mark any fixed astronomical moment such as a solstice, only the calendar's own internal turning point. Diego de Landa's account describes the period as one in which communities avoided leaving their houses, refrained from washing or combing hair, and postponed important undertakings, precautions consistent with the broader Mesoamerican pattern in which liminal, unnumbered days outside the ordinary calendar were treated as ritually dangerous; the unrelated Aztec nemontemi, five comparable closing days in the 365-day xiuhpohualli, were regarded with similarly marked unease, though the two traditions' specific practices are independently attested and should not be assumed identical.