hypomagnesemia Syllabification: (hy·po·mag·ne·se·mi·a)Pronunciation: /ˌhīpəˌmagnəˈsēmēə/ (Britishhypomagnesaemia)Definition of hypomagnesemia noun Medicine & Veterinary deficiency of magnesium in the blood, significant in cattle as the cause of grass tetany. Derivatives hypomagnesemicPronunciation: /-ˈsēmik/ adjective hypomagnesemia in other Oxford dictionaries Definition of hypomagnesemia in the British & World English dictionary