'pigpen' originates from Middle English, specifically the words 'pig' and 'pen', where 'pig' referred to the animal and 'pen' meant an enclosure.

'pigpen' changed from the Middle English word 'piggepenne' and eventually became the modern English word 'pigpen'.

Initially, it meant 'an enclosure for pigs', but over time it evolved to also mean 'a messy or dirty place'.