incidence

C1 Topic:Abstract Ideas

US /ˈɪn.sɪ.dəns/ See IPA manual

Freq #38409

Meanings

1

noun
How often something happens, especially something unwanted.

There has been a rise in the incidence of flu this winter.
2

noun
The way a beam of light or radiation strikes a surface.

She measured the angle of incidence of the reflected light.

Thesaurus

Synonyms

1 noun · how often something... relative incidence

Word family

Forms incidences

Derived forms nonincidenceseroincidence

Appears in

Phrases (1)

See all

incidence angle
the angle between an incoming ray and a line perpendicular to a surface

Noun + noun

Etymology

From Middle French incidence, from Medieval Latin incidentia (“a falling upon”), from Latin incidens, present participle of incidere (“to fall upon”), from in (“on”) + cadere (“to fall”).

*ḱh₂d- Proto-Indo-European incidence Middle French incidentia la-med incidens Latin

View etymology graph ->

Topics

Abstract Ideas Word Formation & Derivatives

External links

# incidence

**Type:** Word
**Level:** C1
**Part of speech:** noun
**IPA (US):** /ˈɪn.sɪ.dəns/
**Frequency rank:** 38409

## Meanings
1. How often something happens, especially something unwanted.
2. The way a beam of light or radiation strikes a surface.

## Examples
- There has been a rise in the incidence of flu this winter.
- She measured the angle of incidence of the reflected light.

## Derived Forms
- nonincidence
- seroincidence

## Roots and Affixes
- Root: *ḱh₂d-
- Root: incidence
- Root: incidentia
- Root: incidens

## Etymology
From Middle French incidence, from Medieval Latin incidentia (“a falling upon”), from Latin incidens, present participle of incidere (“to fall upon”), from in (“on”) + cadere (“to fall”).

## AI Etymology
Incidence comes from Middle French incidence, from Medieval Latin incidentia (“a falling upon”), from Latin incidens, present participle of incidere (“to fall upon”), from in (“on”) + cadere (“to fall”). The historical chain includes *ḱh₂d- (Proto-Indo-European), incidence (Middle French), incidentia (Medieval Latin), and incidens (Latin). The surrounding word family includes derived forms such as nonincidence and seroincidence. In present use it covers how often something happens, especially something unwanted and the way a beam of light or radiation strikes a surface.

## Topics
- Abstract Ideas
- Word Formation & Derivatives

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