chief petty officer
- (Canada, Navy) A warrant officer belonging to one of the two classes of chief petty officer: chief petty officer first class and chief petty officer second class.
- (Britain, Navy) A non-commissioned officer in the Royal Navy, ranking above petty officer and below warrant officer class 2.
- (US, Navy) A non-commissioned officer in the United States Navy and United States Coast Guard, ranking above petty officer first class and below senior chief petty officer.
- CPO (abbreviation)