In the armed forces or uniformed services, an officer is someone who occupies a position of leadership over their peers.
When used in its widest meaning, the word "officer" refers to commissioned officers, non-commissioned officers, and warrant officers, among other positions. However, when the word is used without additional qualification, it nearly usually refers to solely commissioned officers, who are the more senior members of a force who receive their authority from a commission from the chief of state or governor.