Definition

1. Noun:
   • The striking or falling of something, especially light or radiation, upon a surface: In physics and geometry, "incidence" refers to the event of a ray, line, or particle hitting a surface.
   • The rate, range, or frequency of occurrence of something: In statistics, medicine, and social sciences, "incidence" refers to how often something, such as a disease or event, happens within a specific population and time period.

Usage Examples

• Physics/Geometry:

  • The angle of incidence equals the angle of reflection. (The angle at which a light ray hits a surface is equal to the angle at which it bounces off.)
  • The laser's incidence on the sensor was perfectly perpendicular. (The laser beam struck the sensor at a perfect 90-degree angle.)

• Statistics/Medicine:

  • The study reported a high incidence of flu cases this winter. (The study reported that flu cases occurred frequently this winter.)
  • There is a low incidence of this rare genetic disorder. (This rare genetic disorder occurs infrequently.)

Advanced Usage

• "Angle of incidence": The angle between an incoming ray (like light) and a line perpendicular to the surface it strikes.
  • Pilots must understand how the angle of incidence affects lift on the wings.
• "Incidence rate": A measure of the frequency with which new cases of a disease or event occur in a population during a specified period.
  • The annual incidence rate of the disease was calculated per 100,000 people.

Variants and Related Words

• Incident (noun): An event or occurrence, often one that is unusual or noteworthy.
  • A strange incident was reported last night.
• Incidental (adjective): Occurring as a minor or secondary consequence; not central.
  • The travel costs are incidental to the main project budget.

Synonyms

• Occurrence: The fact or frequency of something happening.
• Prevalence: The fact or condition of being common or widespread (often used similarly but can imply existing cases, while "incidence" typically refers to new cases).
• Rate: A measure, quantity, or frequency.

Related Phrases

• Point of incidence: The specific point where a ray or line meets a surface.
  • The point of incidence was marked on the diagram for clarity.
• Tax incidence: (Economics) The analysis of who ultimately bears the economic burden of a tax.
  • The economist discussed the tax incidence on consumers versus producers.

Noun

1. the striking of a light beam on a surface
   • he measured the angle of incidence of the reflected light
2. the relative frequency of occurrence of something