Pigsties are structures used to house pigs. They are typically made of wood, metal, or concrete and can be either open or enclosed. Messes, which is a six-letter word for the crossword solution, refers to the state of the pigsty, which is usually quite messy due to the pigs' habit of rooting around in the dirt. PENS, which is a four-letter word for the crossword solution, refers to the area within the pigsty where the pigs are kept.