adamantine

adjective

ad·​a·​man·​tine ˌa-də-ˈman-ˌtēn 

-ˌtīn, 

-ˈman-tᵊn

1

: made of or having the quality of adamant

2

: rigidly firm : unyielding

adamantine discipline

3

: resembling the diamond in hardness or luster

Did you know?

The Greek and Latin word for the hardest imaginable substance, whether applied to a legendary stone or an actual substance, such as diamond, was adamas. Latin poets used the term figuratively for things lasting, firm, or unbending, and the adjective adamantinus was applied in similar contexts. The English noun adamant (meaning "an unbreakable or extremely hard substance") as well as the adjective adamant ("inflexible" or "unyielding") came from adamas. Adamantine, however—which has such figurative uses as "rigid," "firm," and "unyielding"—came from adamantinus. Adamas is also the source of diamond. Diamas, the Latin term for diamond, is an alteration of adamas.

Synonyms of adamantine

• adamant
• stubborn
• steadfast
• hardened

Examples of adamantine in a Sentence

the adamantine opposition of his parents to his marriage to a girl from a poor family

Recent Examples on the Web

During Vargas Llosa’s lifetime, his political beliefs underwent extreme changes, from supporting Castro’s revolutionary Communism to championing traditional European liberalism, which included an adamantine belief in unregulated markets. — Literary Hub, 26 Feb. 2026

Image My first collision with the adamantine wall of Vivamayr house rules coincided with my arrival. — Caity Weaver, New York Times, 25 Jan. 2025

This poor little deer had to be sacrificed by your adamantine reviewer to show you how the new tool works. — PCMAG, 30 May 2024

She is known for her aphoristic precision and intense, adamantine paragraphs. — Matthew Gavin Frank, Harper's Magazine, 21 Feb. 2022

This view is much in vogue today, casting China not as a country that responds to pressure and incentives but as an adamantine force incapable of reacting to external stimuli. — Julian Gewirtz, Foreign Affairs, 13 Oct. 2020

Word History

Etymology

Middle English, borrowed from Anglo-French, borrowed from Latin adamantinus, borrowed from Greek adamántinos, derivative of adamant-, adámas adamant entry 2

First Known Use

13th century, in the meaning defined at sense 1

Rhymes for adamantine

• acetylene
• adenosine
• amphetamine
• anthropocene
• apoprotein
• aquamarine
• arsphenamine
• azobenzene
• buprenorphine
• catecholamine
• chlorobenzene
• chlorpromazine

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Kids Definition

adamantine

adjective

ad·​a·​man·​tine ˌad-ə-ˈman-ˌtēn 

-ˌtīn

1

: made of or having the quality of adamant

2

: adamant entry 2

Medical Definition

adamantine

adjective

ad·​a·​man·​tine ˌad-ə-ˈman-ˌtēn  -ˌtīn  -ˈmant-ᵊn 

: characterized by extreme hardness or luster