fathomless

adjective

fath·​om·​less ˈfa-t͟həm-ləs 

: incapable of being fathomed : immeasurable

fathomless powers of gravity and chemistry

—R. W. Emerson

fathomlessly adverb

fathomlessness noun

Synonyms

• bottomless
• boundless
• endless
• horizonless
• illimitable
• immeasurable
• immensurable
• indefinite
• infinite
• limitless
• measureless
• unbounded
• unfathomable
• unlimited

Examples of fathomless in a Sentence

impresses everyone with her fathomless knowledge of wildcats

Recent Examples on the Web

Glaciers of the Pleistocene epoch, which retreated about 14,000 years ago, left behind the rolling landscape of craggy granite peaks, sloping valleys, and fathomless lakes. —Alex Tzelnic, Outside Online, 6 June 2025

The sky is vast and fathomless. —Brian T. Allen, National Review, 15 Feb. 2025

Think of the famous scene: wise men navigating by the stars—flaming constellations against a fathomless sky—searching the dank nooks of Rome’s empire for an incandescent child. —Vinson Cunningham, The New Yorker, 25 Dec. 2024

Their relationship climaxes with a verbal showdown late in the season that is almost unbearable to watch, as Sanada and Nishioka summon the fathomless love and respect underlying the confrontation. —Kristen Baldwin, EW.com, 27 Feb. 2024

Word History

First Known Use

1638, in the meaning defined above