The term BUS can be broken down into three job descriptions: EXEC (4 letters), CEO (3 letters), and MGR (3 letters). An EXEC is a high-level executive, usually in charge of a large organization or company. A CEO is the Chief Executive Officer, the highest-ranking executive in a company and the one responsible for making major decisions. Lastly, a MGR is a Manager, someone who oversees the work of a team or department and is responsible for their performance.