fastness: meaning, definition, pronunciation and examples

C1/C2 (Low-frequency, literary/technical)
UK/ˈfɑːs(t)nəs/US/ˈfæs(t)nəs/

Formal, Literary, Technical (e.g., textiles, mountaineering, archaic military)

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Quick answer

What does “fastness” mean?

The quality or condition of being fixed, firm, or not easily moved.

Audio

Pronunciation

Definition

Meaning and Definition

The quality or condition of being fixed, firm, or not easily moved; a secure, fortified place.

The quality of being resistant to fading or colour change; steadfastness, constancy. Also refers to a remote stronghold or fortress.

Dialectal Variation

British vs American Usage

Differences

In BrE, 'fastness' is slightly more common in historical/geographical contexts (e.g., mountain fastness). In AmE, its primary technical use is in textiles ('colour fastness'). Both are very low frequency.

Connotations

BrE: archaic, romantic, descriptive of landscape. AmE: technical, industrial. Both share the literary connotation of an isolated retreat.

Frequency

Extremely low in general conversation. Higher frequency in specific domains: fabric manufacturing, fantasy literature, historical writing.

Grammar

How to Use “fastness” in a Sentence

the fastness of [something] (e.g., the fastness of the dye)seek refuge in a [descriptor] fastness (e.g., a mountain fastness)

Vocabulary

Collocations

strong
colour fastnessmountain fastnessremote fastnessimpregnable fastness
medium
secure fastnessancient fastnesstest the fastnessrated for fastness
weak
dark fastnessnatural fastnessgreat fastnessinner fastness

Examples

Examples of “fastness” in a Sentence

verb

British English

  • Not applicable. 'Fastness' is a noun only.

American English

  • Not applicable. 'Fastness' is a noun only.

adverb

British English

  • Not applicable. 'Fastness' is a noun only.

American English

  • Not applicable. 'Fastness' is a noun only.

adjective

British English

  • Not applicable. 'Fastness' is a noun only.

American English

  • Not applicable. 'Fastness' is a noun only.

Usage

Meaning in Context

Business

Rare, except possibly in textile or dye manufacturing: 'The fabric's colour fastness meets industry standards.'

Academic

Used in historical/geographical texts: 'The rebels retreated to their mountain fastness.'

Everyday

Virtually never used in everyday conversation.

Technical

Common in textiles: 'light fastness', 'wash fastness'; also in mountaineering for a secure climbing position.

Vocabulary

Synonyms of “fastness”

Vocabulary

Antonyms of “fastness”

Watch out

Common Mistakes When Using “fastness”

  • Using it to mean 'speed' (e.g., 'the fastness of the car').
  • Using it in casual contexts where 'strength', 'security', or 'fortress' would be more natural.
  • Pronouncing it with a short 'a' in BrE (should be long /ɑː/).

FAQ

Frequently Asked Questions

No. It derives from the Old English 'fæst' meaning 'firm, fixed, secure', not the modern meaning of 'quick'. They are etymological homographs.

It would sound very formal or archaic. In most contexts, use 'fortress', 'stronghold', or 'colour-fast quality' instead.

It is a technical term from textiles meaning the resistance of a dye or colour to fading or running when exposed to light, washing, or other agents.

No, it is a low-frequency, specialised word. You will encounter it primarily in technical manuals (textiles), historical writing, or fantasy literature.

The quality or condition of being fixed, firm, or not easily moved.

Fastness is usually formal, literary, technical (e.g., textiles, mountaineering, archaic military) in register.

Fastness: in British English it is pronounced /ˈfɑːs(t)nəs/, and in American English it is pronounced /ˈfæs(t)nəs/. Tap the audio buttons above to hear it.

Phrases

Idioms & Phrases

  • None. 'Fastness' is not used in common idioms.

Learning

Memory Aids

Mnemonic

Think of a FAST (firm) NESS (place or state) – a firm place like a fortress, or the firm state of a colour that won't run.

Conceptual Metaphor

STEADFASTNESS IS BEING FIRMLY ANCHORED / SECURITY IS A FORTRESS.

Practice

Quiz

Fill in the gap
The laboratory tested the fabric's to washing and sunlight.
Multiple Choice

In which context is 'fastness' most commonly used today?