Wiktionary
n. A 13-day period used in pre-Columbian Mesoamerican calendars.
Wikipedia
A trecena is a 13-day period used in pre-Columbian Mesoamerican calendars. The 260-day calendar (the tonalpohualli) was divided into 20 trecenas. Trecena is derived from the Spanish chroniclers and translates to "a group of thirteen" in the same way that a dozen (or in Spanish docena) relates to the number twelve. It is associated with the Aztecs, but is called different names in the calendars of the Maya, Zapotec, Mixtec, and others of the region.
Many surviving Mesoamerican codices, such as Codex Borbonicus, are divinitory calendars, based on the 260-day year, with each page representing one trecena.
n.º
Trecena
Aztec deities associated
Cardinal point
1
1 Cipactli (Caiman or aquatic monster)
Tonacatecuhtli
East
2
1 Ehecatl (Wind)
Quetzalcoatl
North
3
1 Calli (House)
Tepeyollotl, Quetzalcoatl
West
4
1 Cuetzpallin (Lizard)
Huehuecoyotl or Macuilxochitl
South
5
1 Coatl (Snake)
Chalchiuhtlicue and Tlazolteotl
East
6
1 Miquiztli (Death)
Tonatiuh and Tecuciztecatl
North
7
1 Mazatl (Deer)
Tlaloc and Chicomecoatl o 4 Ehécatl
West
8
1 Tochtli (Rabbit)
Mayahuel and Xochipilli or Cinteotl
South
9
1 Atl (Water)
Tlahuizcalpantecuhtli or Xiuhtecuhtli
East
10
1 Itzcuintli (Dog)
Mictlantecuhtli
North
11
1 Ozomatli (Monkey)
Patecatl and Cuauhtliocelotl
West
12
1 Malinalli (Grass)
Itztlacoliuhqui
South
13
1 Acatl (Reed)
Tezcatlipoca or Uactli and Ixcuina or Tlazolteotl
East
14
1 Ocelotl ( Ocelot or Jaguar)
Tlazolteotl
North
15
1 Cuauhtlil (Eagle)
Xipe Totec and Quetzalcoatl
West
16
1 Cozcacuauhtli (Vulture)
Itzpapalotl
South
17
1 Ollin (Movement or Earthquake)
Xolotl and Tlalchitonatiuh or 4 Ollin
East
18
1 Tecpatl (Flint or Knife)
Chalchiuhtotolin
North
19
1 Quiahuit (Rain)
Tonatiuh
West
20
1 Xochitl (Flower)
Xochiquetzal and Tezcatlipoca
South