The senior officer of a service of the armed forces WordNet 3.0 & Open English WordNet

The title chief of staff identifies the leader of a complex organization such as the Armed Forces, institution, or body of persons and it also may identify a principal staff officer, who is the coordinator of the supporting staff or a primary aide-de-camp to an important individual, such as a president, or a senior military officer, or leader of a large organization. Wikipedia

The leader of a complex organization Wikipedia Disambiguation

Identifies the leader of a complex organization, institution, or body of persons Wikidata

The senior officer of any of several services of the armed forces of several nations. Wiktionary

Senior officer. Wiktionary (translation)