top-secret

American  

[top-see-krit] / ˈtɒpˈsi krɪt /

adjective

1. bearing the classification top-secret, the highest level of classified information.

2. limited to persons authorized to use anything so classified.

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top-secret British  

adjective

1. containing information whose disclosure would cause exceedingly grave damage to the nation and therefore classified as needing the highest level of secrecy and security

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Etymology

Origin of top-secret

First recorded in 1940–45; top ¹ + secret

Explanation

Have you sworn not to reveal the information in a thick file of papers? Then you can describe it as top-secret or classified — it is confidential, and must not be publicized or shared. If you work for the CIA or the FBI some day, you'll likely be responsible for top-secret information. A top-secret mission might mean that you aren't allowed to tell anyone where you're going or what you are doing there. When a government or company classifies something as top-secret, it's either because revealing it could harm people or because it could harm business interests. The recipe for fried chicken at your favorite fast food place? It's top-secret.

Example Sentences

Historically, Los Alamos served as the top-secret heart of the Manhattan Project, where the first atomic bombs were designed and built on an expedited timeline.

From Barron's • Apr. 23, 2026

“So it was an Energy and Commerce top-secret effort?”

From Slate • Mar. 18, 2026

Aurelio Perez-Lugones, a system administrator with a top-secret security clearance, is suspected by the DOJ of taking classified material.

From Salon • Jan. 14, 2026

Now, heading into their fourth winter of war, the country’s energy suppliers are banking on a network of massive, U.S.-designed batteries held at top-secret locations to help keep the lights on.

From The Wall Street Journal • Oct. 6, 2025

Not when I’m holding top-secret correspondence from my runaway mother.

From "South of Somewhere" by Kalena Miller