'magnesium-rich' originates from New Latin, specifically the word 'magnesium' (from Greek 'Magnesia', a place name associated with magnetite) combined with the English suffix '-rich' which comes from Old English 'rice', where 'rice' meant 'powerful, wealthy' and later formed adjectives meaning 'abounding in'.

'magnesium' entered scientific English via New Latin 'magnesium' from the Greek place name 'Magnesia'; the suffix '-rich' evolved from Old English 'rice' through Middle English into a productive modern English suffix used to form compounds (e.g. 'sugar-rich', 'iron-rich'), and the modern compound 'magnesium-rich' developed to describe substances abundant in magnesium.

Initially, 'magnesium' named the element associated with Magnesia and '-rich' meant 'abounding in' or 'wealthy in'; over time their combination came to be used specifically to describe materials or diets that contain a high amount of magnesium.