sunglass

Thân thiện

A hiker uses a sunglass to ignite dry leaves.

Definition

1. Noun:
   • A convex lens that focuses the sun's rays: A "sunglass" is a single optical lens, typically convex, designed to concentrate sunlight into a small, intense point of heat, historically used for igniting tinder or starting fires.

Usage Examples

• Noun:
  • He used a powerful sunglass to light the dry leaves.
  • Before matches, a sunglass was a common tool for fire-starting.

Advanced Usage

• Historical/Scientific Context: The term "sunglass" in this sense is largely archaic and technical. It refers specifically to the fire-starting tool, not modern eye protection.
  • The survival kit included a magnifying glass that could function as a sunglass.

Variants and Related Words

• Magnifying glass: A general term for a convex lens used to magnify objects, which can also serve as a sunglass.
• Burning glass: A near-synonym specifically emphasizing the fire-starting function of a convex lens.

Synonyms

• Burning glass: A lens used to start fires by focusing sunlight.
• Fire lens: A descriptive term for a lens used to ignite fires.

Notes on Common Confusion

• Important Distinction: This definition of "sunglass" is distinct from the much more common modern term "sunglasses" (always plural), which refers to tinted eyewear for protecting the eyes from sunlight. They are different words with different meanings.
  • Incorrect: He wore his sunglass to the beach. (This would be incorrect for the fire-starting tool and atypical for eye protection; "sunglasses" is the correct term for eyewear.)
  • Correct (for eyewear): He wore his sunglasses to the beach.

Học thuật

Noun

1. a convex lens that focuses the rays of the sun; used to start a fire