Chief of Staff

American  

noun

1. the senior officer of the U.S. Army or Air Force, a member of the Joint Chiefs of Staff, responsible to the secretary of a service branch.

2. (lowercase) the senior or principal staff officer in a brigade or division or higher unit in the U.S. Army or Marine Corps, in a numbered unit in the U.S. Air Force, or in a unit in the U.S. Navy commanded by a rear admiral or one of higher rank.

3. (lowercase) the senior officer in command of a general staff, especially that of the military forces of a nation.

4. (lowercase) the head of any staff.

   the chief of staff for the First Lady.

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Chief of Staff British  

noun

1. the senior staff officer under the commander of a major military formation or organization

2. the senior officer of each service of the armed forces

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Etymology

Origin of Chief of Staff

First recorded in 1880–85

Example Sentences

The central figure making this case, according to several accounts, is Gen. Dan Caine, the Trump-appointed chairman of the Joint Chief of Staff.

From Slate • Feb. 28, 2026

A similar call, this time from current Chief of Staff Susie Wiles, again brought him out of retirement in 2024 ahead of the second administration.

From BBC • Jan. 27, 2026

And in an interview with Vanity Fair late last year, White House Chief of Staff Susie Wiles said that “it is categorically false, will not happen.”

From Salon • Jan. 26, 2026

Chief of Staff Susie Wiles cited administration missteps on immigration and the Jeffrey Epstein case and acknowledged President Trump’s retribution campaign.

From Los Angeles Times • Dec. 20, 2025

The Interim Committee met with its scientific panel for the first time on May 31 at the Pentagon, with Groves and Army Chief of Staff George C. Marshall in attendance.

From "Big Science" by Michael Hiltzik