magnetohydrodynamicsPronunciation: /magˌniːtəʊˌhʌɪdrə(ʊ)dʌɪˈnamɪks/Definition of magnetohydrodynamics noun [treated as singular] the branch of physics that studies the behaviour of an electrically conducting fluid (such as a plasma or molten metal) acted on by a magnetic field. Derivatives magnetohydrodynamic adjective magnetohydrodynamics in other Oxford dictionaries Definition of magnetohydrodynamics in the US English dictionary