fathomless

American  

[fath-uhm-lis] / ˈfæð əm lɪs /

adjective

1. impossible to measure the depth of; bottomless.

2. impossible to understand; incomprehensible.

   fathomless motives.

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fathomless British  

/ ˈfæðəmlɪs /

adjective

1. another word for unfathomable

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Other Word Forms

• fathomlessly adverb
• fathomlessness noun

Etymology

Origin of fathomless

First recorded in 1600–10; fathom + -less

Explanation

Something fathomless is so deep or great that you can’t measure it, or so mysterious that nobody can understand it. If you were an ant, you’d probably think the kitchen sink was fathomless — and also the whole business of washing dishes! Fathomless means about the same as the more common word unfathomable. You might choose fathomless in a poem, or in any piece of writing where you want to sound a little more elegant or literary — or use three syllables instead of five! In your reading you might come across expressions like "fathomless oceans" or "the fathomless universe." Figuratively, knowledge, love, evil, and wealth are often described as fathomless.

Example Sentences

Scene by scene, Ms. Alexander deftly conveys the mounting burden of Carol’s exhaustion and fathomless sadness in the face of this.

From The Wall Street Journal • Mar. 26, 2026

The end of the shipping container is open, and I stare into that fathomless black square, listening.

From Slate • Apr. 29, 2023

I’ll pull out just one such gem, for it illustrates the timeliness of the author’s approach to the fathomless depths of his subject.

From Washington Post • Oct. 25, 2022

But over the years, the song has revealed itself to contain fathomless depths that have only been audible in later interpretations.

From New York Times • Jul. 26, 2022

Otherwise I could be chased off this pitching deck and into the fathomless sea.

From "Secrets at Sea" by Richard Peck

Related Words

• baffling
• impenetrable
• inconceivable
• mystifying
• opaque
• puzzling
• unfathomable
• unimaginable
• unintelligible