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• true blue
  true blue

  noun

  a nonfading blue dye or pigment.
• true-blue
  true-blue

  adjective

  unwaveringly loyal or faithful; staunch; unchangingly true.

true blue

¹ American  

noun

1. a nonfading blue dye or pigment.

2. a person who is true-blue.

3. (in the 17th century) the color adopted by the Covenanters in contradistinction to the royal red.

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true-blue ² American  

[troo-bloo] / ˈtruˈblu /

adjective

1. unwaveringly loyal or faithful; staunch; unchangingly true.

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true-blue British  

adjective

1. unwaveringly or staunchly loyal, esp to a person, a cause, etc

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noun

1. a staunch royalist or Conservative

true blue Idioms  

1. Loyal, faithful, as in You can count on her support; she's true blue. This expression alludes to the idea of blue being the color of constancy, but the exact allusion is disputed. One theory holds it alludes to the unchanging blue sky, another to the fastness of a blue dye that will not run. Blue has been the identifying color of various factions in history. In the mid-1600s the Scottish Covenanters, who pledged to uphold Presbyterianism, were called true blue (as opposed to red, the color of the royalists). In the 1800s the same term came to mean “staunchly Tory,” and in America, “politically sound.”

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Etymology

Origin of true blue¹

First recorded in 1665–75

Origin of true-blue²

First recorded in 1665–75; origin uncertain; perhaps associated with the Covenanters (Scottish Presbyterians) of the 17th century, whose flag, a white St. Andrew’s Cross on a blue field (still the national flag of Scotland), was in opposition to the red scarves of the Royalist cavalry

Example Sentences

See Examples For:

true blue true-blue

She needs all the friends she can get, and the Twin Cities folks are true blue.

From Los Angeles Times ● Jan. 15, 2026

Naturally, I'm a true blue Aussie, but that doesn't mean I can't like the way England play.

From BBC ● Jun. 27, 2023

Only one class of plant pigments has achieved a true blue: anthocyanins.

From Science Magazine ● Jun. 14, 2023

My mother is an ardent egg avoider and a true blue brunch hater, so that hasn't been the case for us — but that is neither here nor there!

From Salon ● May 11, 2023

Which made any upright, true blue Milagro citizen, knowing the odds in favor of the early Death of the Fruit Tree Blossoms, just about vomit.

From "The Milagro Beanfield War" by John Nichols

His presence campaigning can enthuse his true-blue supporters.

From The Wall Street Journal ● May 20, 2026

One prince is an "absolute true-blue legend" whose vibrant eyes "blazed like a bushfire" while another is a "bit of a yobbo" who thinks others are "carrying on like a pack of galahs".

From BBC ● Nov. 14, 2025

Harrison was a true-blue jazz musician, and Adjuah — who was born, and first introduced to the listening public as, Christian Scott — seemed destined to become one, too.

From New York Times ● Jul. 27, 2023

This is a true-blue house shoe: deeply uncomfortable and designed for short-distance travel.

From Los Angeles Times ● Mar. 15, 2023

She once called Lucy my “some-timey friend,” meaning Lucy wasn’t true-blue.

From "P.S. Be Eleven" by Rita Williams-Garcia