A course of action (COA) is 1. Any sequence of activities that an individual or unit may follow. 2. A possible plan open to an individual or commander that would accomplish, or is related to the accomplishment of the mission. 3. The scheme adopted to accomplish a job or mission. 4. A line of conduct in an engagement. 5. A product of the Joint Operation Planning and Execution System concept development phase. 6. A mode of action. 7. A plan that would accomplish, or is related to, the accomplishment of a mission.

from U.S. Joint Forces Command Glossary
www.jfcom.mil/about/glossary.htm