Cow pen is a term used to describe a confined area where cows are kept. However, there are several other synonyms for this term. One of the commonly used synonyms is "cow enclosure." This term is used to describe a fenced area where cows are kept. Another synonym is "cowshed," which refers to a building where cows are kept or milked. "Barnyard" and "cattle yard" are two other synonyms used for a cow pen. Additionally, the terms "pasture" and "grazing field" are used to describe larger areas of land where cows can roam freely. Overall, there are several synonyms for the term "cow pen," each with a specific meaning that describes the area in which cows are kept.