Definition

1. Noun:
   • An imaginary straight line along which an observer looks: This is the direct, unobstructed path between an observer's eye and a point or object being viewed.

Usage

• The term is used to describe the visual connection between a viewer and a target. It is a fundamental concept in fields like optics, ballistics, telecommunications, and architecture.
• It often implies that nothing is blocking the view. If something is "in the line of sight," it obstructs vision. If something is "out of the line of sight," it cannot be seen directly.

Examples

• Noun:
  • The sniper had a clear line of sight to the target.
  • Tall buildings disrupted the line of sight for the satellite dish.
  • Make sure the presenter has an unobstructed line of sight to the audience.

Advanced Usage

• "Line-of-sight" (Adjective form): Used attributively to describe things that require a direct visual path.

  • Infrared remote controls are a line-of-sight technology.
  • The military uses line-of-sight communication for certain radios.

• "Within/out of line of sight": Phrases describing visibility.

  • The bird remained within my line of sight until it flew behind the hill.
  • The treasure was hidden just out of the guard's line of sight.

Variants and Related Words

• Line of vision: A very close synonym, often used interchangeably.
• Visual axis: A more technical term used in optics and eye physiology.
• Sightline: A common variant, especially in theater, stadium design, and urban planning, referring to an observer's line of sight to a stage, screen, or vista.
  • The new building ruined the sightline to the mountains from the park.

Synonyms

• Line of vision
• Sightline
• Visual path
• Direct view

Related Phrases

• Clear line of sight: A completely unobstructed view.

  • For the experiment, we need a clear line of sight between the laser and the sensor.

• In the line of fire: While related to trajectory rather than sight, this idiom is conceptually similar, meaning in the path of something dangerous (like bullets). It is important to distinguish it from "line of sight."

  • The civilians were caught in the line of fire. (This is not a synonym for "line of sight").

Noun

1. an imaginary straight line along which an observer looks