From Longman Dictionary of Contemporary Englishcardiocar‧di‧o /ˈkɑːdiəʊ $ ˈkɑːrdioʊ/ noun [uncountable] informal any type of exercise that makes the heart stronger and healthier, for example running a combination of cardio, weight training, and kung fucardio-cardio- /kɑːdiəʊ, -diə $ kɑːrdioʊ, -diə/ prefix medical HBHrelating to the heart a cardiograph (=machine that measures movements of the heart)Origin cardio- Greek kardia “heart”