active duty

American  

noun

Military.

1. the status of full-time service.

   on active duty.

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active duty Idioms  

1. Full-time service, as in Julian is 81, but he still comes to the office every day and is very much on active duty. This term comes from the military, where it stands in opposition to reserve, which refers to troops still in the military but not actively engaged. It is occasionally transferred to civilian matters as well. [First half of 1800s]

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Example Sentences

Kelly could even be recalled to active duty, then court-martialed, an act that would remove his military status entirely and even land the senator in prison.

From Slate • Jan. 13, 2026

Some western estimates put its active duty contingent in the hundreds of thousands, still a very substantial total.

From BBC • Jan. 13, 2026

Ross served in the Indiana National Guard and was deployed to active duty.

From The Wall Street Journal • Jan. 9, 2026

A large hospital was recently added, and there are various buildings for the base’s more than 42,000 active duty personnel.

From Los Angeles Times • Sep. 28, 2025

He ordered the doctors to make Oppenheimer eligible for active duty.

From "Bomb" by Steve Sheinkin