Existing definitions of the term hypogene karst (hypogene speleogenesis) are not always consistent with the established meaning of the term hypogene in the Earth Sciences. They are commonly biased either toward geochemical or toward hydrogeological aspects of the phenomenon. It is proposed that hypogene karst is defined on the basis of the two properties: predominance of the deep-seated sources of aggressiveness of karst water, independent of the environment at the overlying or immediately adjacent surface; and recharge of soluble formation from below, independent of recharge from overlying or immediately adjacent surface