'hydrogen-rich' originates from Modern English, specifically a compound of 'hydrogen' and 'rich'; 'hydrogen' ultimately comes from Greek (Ancient Greek) 'hydrogénēs' (from 'hydro-' meaning 'water' and 'génēs' meaning 'born/producing'), and 'rich' comes from Old English 'rice' meaning 'wealthy/abundant'.

'hydrogen' entered scientific vocabulary in the 18th century via French 'hydrogène' (coined in chemical nomenclature), while 'rich' evolved from Old English 'rice' to Middle English and modern English 'rich'; the compound 'hydrogen-rich' is a Modern English formation combining these elements.

Initially, 'hydrogen' denoted 'water-forming' (from Greek) and 'rich' denoted 'wealthy/abundant'; over time the compound came to mean 'abundant in hydrogen' in scientific and technical contexts.