The term 'PEN FOR LIVESTOCK' can be summarized by the crossword solution CORRAL, which is a six-letter word. A CORRAL is an enclosure made of posts and rails, or other materials, used to contain livestock such as horses, cattle, and sheep. Corrals are typically used for keeping animals in one place, or for separating different types of animals. They are also used for branding, sorting, and loading animals onto trucks or trailers.