constancy

noun

con·​stan·​cy ˈkän(t)-stən(t)-sē 

plural constancies

1

a

: steadfastness of mind under duress : fortitude

b

: fidelity, loyalty

2

: a state of being constant or unchanging

Synonyms

• changelessness
• fixedness
• immutability
• immutableness
• invariability
• stability
• steadiness
• unchangeableness

Examples of constancy in a Sentence

the constancy of the Earth's rotation

the mistaken notion that there is constancy in language—words do indeed change their meanings over time

Recent Examples on the Web

Gold’s constancy explains why it’s long been used to define money. —John Tamny, Forbes.com, 11 May 2025

But dark energy’s constancy has always been more of a clever inference rather than an ironclad certainty. —Lyndie Chiou, Scientific American, 30 Apr. 2025

Debra Messing, who has produced a new documentary on (horseshoe-theory) antisemitism called October 8, has been one of Hollywood’s few intensely admirable exceptions, calling out anti-Jewish hatred with a fierce constancy over the past 16 months. —Steven Zeitchik, The Hollywood Reporter, 1 Mar. 2025

In the 1940s scientists realized this cosmic constancy could be used to measure time without the chaotic noise associated with other physical clocks. —Allison Parshall, Scientific American, 11 Sep. 2024

Word History

First Known Use

15th century, in the meaning defined at sense 1a

Rhymes for constancy

• inconstancy

Kids Definition

constancy

noun

con·​stan·​cy ˈkän(t)-stən-sē 

plural constancies

1

: firmness and loyalty in one's beliefs or personal relationships

2

: freedom from change