'high-fat' is a compound word formed from 'high' and 'fat'. 'High' originates from Old English 'hēah', meaning 'of great height', and 'fat' comes from Old English 'fǣtt', meaning 'well-fed' or 'plump'.

'High-fat' evolved as a descriptive term in modern English to denote foods or diets rich in fat content.

Initially, 'fat' referred to the physical state of being plump, but in modern usage, it often refers to the nutritional content of food.