'cage-free' originates from the English words 'cage' and 'free', where 'cage' meant 'a structure of bars or wires in which birds or other animals are confined' and 'free' meant 'not under the control or in the power of another; able to act or be done as one wishes'.

'cage-free' evolved from the combination of the words 'cage' and 'free' to describe a method of animal husbandry that allows animals more freedom.

Initially, it referred to animals not being confined in cages, and this meaning has remained consistent in modern usage.