Definition

1. Noun:
   • A strongly fortified defensive structure: A secure place, such as a fortress or stronghold, designed to resist attack.
   • The quality of being fixed in place: The state of being firmly attached, secured, or resistant to movement or change.
   • A rate (usually rapid) at which something happens: The speed or swiftness of an action or process.
   • The quality of being resistant to fading or running: The property of a dye or color to remain unchanged when exposed to light, washing, or other agents.

Examples

• As a fortified structure:

  • The rebels retreated to their mountain fastness.
  • The ancient fastness was considered impregnable.

• As the quality of being fixed:

  • The fastness of the bolt ensured the door would not open.
  • They tested the fastness of the knot before climbing.

• As a rate of speed:

  • The fastness of his reply surprised everyone. (Note: This usage is less common; 'speed' or 'rapidity' is often preferred.)
  • She was amazed by the fastness of the chemical reaction.

• As color retention:

  • This fabric is prized for the fastness of its dye.
  • The label guarantees the color's fastness to light and washing.

Advanced Usage

• "Light fastness": A technical term in textiles and art for a material's resistance to fading when exposed to light.

  • Artists' paints are graded for their light fastness.

• "Wash fastness": A technical term for a dye's resistance to running or fading during laundering.

  • The manufacturer tests all materials for wash fastness.

Variants and Related Words

• Fast (adj): Firmly fixed; moving or capable of moving at high speed; (of a dye) not fading.

  • Hold fast to the rope.
  • He is a fast runner.
  • The colors are fast and won't run.

• Fasten (v): To close or attach securely.

  • Please fasten your seatbelt.

Synonyms

• Fortress / Stronghold: For the meaning of a defensive structure.
• Security / Firmness / Stability: For the meaning of being fixed in place.
• Speed / Rapidity / Swiftness: For the meaning of a rapid rate.
• Colorfastness / Permanence: For the meaning of color retention.

Related Phrases

• "Hold fast": To remain firmly secured or to cling firmly to something (like a belief).
  • The ship's anchor held fast during the storm.
  • He held fast to his principles.

Idioms

• "A fastness of the heart" (literary/archaic): Used to describe a deeply held, secure feeling or belief.
  • In her fastness of heart, she knew she was right.

Noun

1. a strongly fortified defensive structure
2. the quality of being fixed in place as by some firm attachment
3. a rate (usually rapid) at which something happens
   • the project advanced with gratifying speed