A cenote is a natural sinkhole that exposes groundwater, and cenotes supplied water at many Maya sites, including Chichén Itzá.
The northern Yucatán Peninsula is a limestone landscape with few surface rivers or permanent lakes. Rainwater filtered through the porous rock and collected in underground aquifers; when limestone roofs collapsed, the water became accessible through cenotes. These natural wells therefore helped determine where major settlements could grow.
Chichén Itzá had several visible cenotes. Its most famous is the Sacred Cenote, a large water-filled sinkhole north of the ceremonial center and connected to it by a raised road. It also had ritual importance: Maya offerings, including valuable objects and human remains, were deposited there in ceremonies associated with Chaac, the rain god.
A common mix-up is treating “cenote” as the name of one particular well. It is a general geological term; “Sacred Cenote” identifies the specific famous sinkhole at Chichén Itzá.