A tinaja [tiˈnaxa] is a surface pocket (depression) formed in bedrock that occurs below waterfalls, that is carved out by spring flow or seepage,[1] or that is caused by sand and gravel scouring in intermittent streams (arroyos).[2][3] Tinajas are an important source of surface water storage in arid environments.[2][4]
These relatively rare landforms are important ecologically, because they support unique plant communities and provide important services to terrestrial wildlife.[5]
The term originates in Spain, being Spanish for "clay jar", and is used in the American Southwest.
The dictionary definition of tinaja at Wiktionary