incidence

 
Pronunciation: /ˈɪnsɪd(ə)ns/

noun

  • 1the occurrence, rate, or frequency of a disease, crime, or other undesirable thing: an increased incidence of cancer
  • the way in which the burden of a tax falls upon the population: the entire incidence falls on the workers
  • 2 [mass noun] Physics the intersection of a line, or something moving in a straight line, such as a beam of light, with a surface: the point of incidence of the beam

Origin:

late Middle English (denoting a casual or subordinate event): from Old French, or from medieval Latin incidentia, from Latin incidere 'fall upon, happen to' (see incident). incidence (sense 1) dates from the early 19th century