unfathomable

/ʌnˈfæðəməbl/ (bre, ipa) · [ənfˈæðəməbəl] /ʌnˈfæðəməbl/ (ame, ipa) · [ənfˈæðəməbəl] /ˌən-ˈfa-t͟hə-mə-bəl How to pronounce unfathomable (audio)/ (ame, mw)

unfathomable — adjective

  • unfathomablepositive
  • more unfathomablecomparative
  • most unfathomablesuperlative

1. so strange, mysterious, or complicated that the human mind cannot make sense of

1.形容詞C1
釋義

so strange, mysterious, or complicated that the human mind cannot make sense of it or explain it — for example, an unfathomable crime, an unfathomable decision, or a person whose expression is impossible to read.

例句

For reasons unfathomable to his coworkers, Bao resigned right before the project deadline.

postpositive: unfathomable to + person

After losing everything in the fire, Greta wore an unfathomable expression that revealed nothing.

collocation: unfathomable expression

同義詞
  • incomprehensible

    the closest synonym, but slightly more common and slightly less literary in tone

  • baffling

    more informal; suggests active confusion or being puzzled rather than a deep mystery

  • mysterious

    broader in meaning and weaker; can describe anything unknown, not just the truly inexplicable

  • impenetrable

    suggests something is deliberately or structurally hard to understand, like impenetrable jargon

反義詞
  • understandable

    common opposite; something the mind can grasp without difficulty

  • comprehensible

    more formal than 'understandable'; the direct antonym of 'incomprehensible'

文法句型

unfathomable + noun

be + unfathomable

unfathomable to + person

用法筆記

Commonly used with intensifiers like 'completely', 'utterly', or 'totally' before the adjective. The postpositive structure 'unfathomable to [somebody]' is typical when specifying whose perspective is being described.

常見錯誤

❌The math problem is unfathomable to understand.
✅The math problem is unfathomable.
💡'unfathomable' already means 'impossible to understand'; adding 'to understand' is redundant.
❌I unfathomable his reasons.
✅His reasons are unfathomable to me.
💡'unfathomable' is an adjective, not a verb; use a linking verb.

2. so deep that the bottom cannot be reached, measured, or even imagined — used lit

2.形容詞C1
釋義

so deep that the bottom cannot be reached, measured, or even imagined — used literally of oceans, chasms, and wells, or hyperbolically of darkness, silence, or emptiness that feels bottomless.

例句

The submarine descended into the unfathomable depths of the Mariana Trench, where no sunlight reaches.

collocation: unfathomable depths

An unfathomable canyon carved by ancient rivers lies hidden beneath the Antarctic ice.

attributive: unfathomable + noun

同義詞
  • bottomless

    more concrete and visual; often used for pits, wells, or holes

  • immeasurable

    focuses on the inability to measure; slightly more technical and less poetic

  • abyssal

    literary or technical; specifically evokes the deep ocean or a terrifying void

  • plumbless

    very rare and poetic; the closest direct synonym from the same root ('fathom' → 'plumb')

反義詞
  • shallow

    everyday opposite; describes a short distance from top to bottom

  • measurable

    focuses on the ability to gauge the depth or extent

文法句型

unfathomable + noun

be + unfathomable

用法筆記

Often used with concrete nouns of space ('depths', 'abyss', 'chasm', 'ocean') but also extended metaphorically to describe darkness, silence, or emptiness that feels infinite. Less common than the abstract sense (sense 1).

常見錯誤

❌The lake is 3 meters deep — unfathomable!
✅The lake is 3 meters deep
💡not unfathomable at all.' — 'unfathomable' implies immeasurable depth; it should not be used for shallow or known depths.