cardiomegalyPronunciation: /ˌkɑːdɪəʊˈmɛgəli/Definition of cardiomegaly noun [mass noun] Medicine abnormal enlargement of the heart. Origin: 1960s: from cardio- + Greek megas, megal- 'great'cardiomegaly in other Oxford dictionaries Definition of cardiomegaly in the US English dictionary