imperceptible

imperceptible — adjective

1. too small, slow, or faint for a person to notice or feel.

1.adjectiveB2
Definition

too small, slow, or faint for a person to notice or feel.

Example

Over many years, the glacier moved at an almost imperceptible speed, reshaping the valley floor.

collocation: almost imperceptible

Leila noticed an imperceptible shift in her mother's tone that others missed.

imperceptible + shift / change / difference

Common collocations
  • almost imperceptible
  • imperceptible to the naked eye
  • imperceptible change / shift / difference
  • nearly imperceptible
Synonyms
  • unnoticeable

    less formal and more common in everyday speech; imperceptible is more precise for extreme subtlety

  • indiscernible

    very close in meaning but slightly more formal; often used for visual differences

  • subtle

    broader in meaning; can describe cleverly indirect or refined details, not just extremely slight ones

Antonyms
  • perceptible

    direct antonym; the exact opposite in formal contexts

  • noticeable

    common opposite in everyday language

  • obvious

    stronger opposite; something easily seen or understood

Usage Note

Often paired with almost (almost imperceptible) or to (imperceptible to the naked eye, imperceptible to someone). More common in written descriptions and formal speech than in everyday conversation.

Common Mistakes

He made an imperceptible mistake in the report.
He made a tiny mistake in the report.
Imperceptible describes something too slight for anyone to detect, not merely a small error.

Word family

  • imperceptibly
    adverbB2
  • imperceptibility
    nounC1
  • perceptible
    adjectiveB2
  • perceptibly
    adverbB2
  • perception
    nounB1

Synonym discussion

Sense: adjective/1

Imperceptible, unnoticeable, indiscernible, and subtle all describe something that is not easily seen or detected, but they differ in degree and context. Imperceptible is the strongest word — it means something is so slight or gradual that a person cannot detect it at all, often used in formal or scientific contexts (an imperceptible change in temperature). Unnoticeable is less formal and milder: an unnoticeable stain on a shirt may simply escape attention without being impossibly faint to detect. Indiscernible is close to imperceptible in formality but focuses on visual perception — two shades so similar they are indiscernible. Subtle is broader and more positive: a subtle flavour or hint carries a refined quality, not just an absence of notice. For everyday situations, unnoticeable feels natural; for absolute lack of detectability, choose imperceptible.

imperceptible ↗unnoticeableindiscerniblesubtle ↗

Common collocations

Nouns

Adverbs

Phrases

  • imperceptible to the naked eye

Prepositions

Etymology

LatinFrenchEnglish

From Latin imperceptibilis, formed by in- (not) and perceptibilis (that can be perceived). The word entered English in the early 1600s through French or directly from Latin, originally used in philosophical writing about ideas too fine for the mind to grasp, later extended to physical sensation.