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.
Pentagon Official Website. The Pentagon is located on the Potomac river in Arlington, VA, just across from Georgetown and Washington, D.C. It gets its name from the shape of the five-sided building.