Commas before conjunctions (e.g., and, or, but). When a word like and, or, and but (called conjunctions) joins two standalone sentences, you should put a comma before it. (The real name for a standalone sentence within a longer sentence is independent clause .).Words like and, or, and but are known as conjunctions.earch. When a word like and, or, and but (called conjunctions) joins two standalone sentences, you should put a comma before it. (The real name for a standalone sentence within a longer sentence is independent clause .).
1. a polygon having five angles and five sides. 2. the Pentagon, a. a building in Arlington, Va., built in the form of a pentagon and containing most of the offices of the U.S. Department of Defense. b. the U.S. Department of Defense; the U.S. military establishment. [1560â70; < Late Latin pentagÅnum < Greek pentÃ¡gÅnon, n. use of neuter of pentÃ¡gÅnos five-angled.
On January 15, 1943, work was completed on the new headquarters for the U.S. War Department (the modern-day Department of Defense) in Arlington, Virginia. The massive complex, commonly known as the Pentagon, was built to house the nearly 30,000 defense workers tasked with helping America win World War II. With more than 17 miles of corridors, it remains one of the largest office buildings in the world, and has become a symbolâfor better and for worseâof military might.