endorheic UK /ˌɛndə(ʊ)ˈɹiːɪk/US /ˌɛndoʊˈɹiɪk/ adjective1 •Of a basin or lake: having no outflow to an external body of water such as a river or ocean, and only losing water through evaporation or seepage into the ground.In the floor of the Rift Valley most of the streams are affected by the tectonic disturbances and are mostly fault-guided besides being endoreic. — 1971