'grass-fed' originates from the combination of 'grass' and 'fed', where 'grass' refers to the green vegetation and 'fed' is the past participle of 'feed', meaning to provide food.

'Grass-fed' evolved from the practice of feeding livestock primarily on grass, a method that has been used for centuries.

Initially, it simply described the diet of animals, but over time it has come to imply a healthier or more natural method of raising livestock.