union jack

American  

noun

1. a jack consisting of the union of a national flag or ensign, as the U.S. jack, which has the white stars and blue field of the union of the U.S. national flag.

2. (often initial capital letter) the British national flag.

3. any flag the overall design of which is a union.

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Union Jack British  

noun

1. a common name for Union flag

2. (often not capitals) a national flag flown at the jackstaff of a vessel

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Etymology

Origin of union jack

First recorded in 1665–75

Example Sentences

Geri Halliwell's union jack flag platform boots are also among items featuring in the free exhibition at the Barbican Music Library, along with Liam Gallagher's tambourine and a Brit Award.

From BBC • Apr. 16, 2026

The Reform UK-led authority's £75,000 project started in December, with 164 union jack flags being fixed to lamp-posts in 82 areas across Nottinghamshire.

From BBC • Jan. 7, 2026

St George and union jack flags have been hung up in public places across several locations in England in recent weeks.

From BBC • Aug. 29, 2025

There have been protests outside some hotels housing asylum seekers where union jack and St George's flags have featured heavily among the placards.

From BBC • Aug. 23, 2025

In the hand is the union jack, on a staff Proper.

From Narrative of the Voyages Round the World, Performed by Captain James Cook : with an Account of His Life During the Previous and Intervening Periods by Kippis, Andrew