Definition of incidence in US English:



  • 1The occurrence, rate, or frequency of a disease, crime, or something else undesirable.

    ‘an increased incidence of cancer’
    • ‘Research from Britain indicates that poor quality housing can increase the incidence of stress and mental illness.’
    • ‘However, he warned if current weather conditions persisted, then the number of reported incidences would increase.’
    • ‘Furthermore, the implementation of a surveillance system may artefactually increase the incidence of a disease.’
    • ‘Higher temperatures will mean increased incidences of vector-borne diseases like malaria, dengue and measles.’
    • ‘Low prevalence is due to a low incidence of the disease but also a high mortality rate.’
    • ‘There is nothing arbitrary or accidental about the incidence of disease.’
    • ‘I am advised that police have adopted a wide range of measures targeted at reducing the incidence of crime.’
    • ‘The value to researchers is that such studies can be most successful in tracking incidences of various common diseases.’
    • ‘Careful selection of cloves at planting can reduce the incidence of this disease.’
    • ‘The incidence of car crime is less than one reported incident per 20,000 car movements.’
    • ‘The incidence of kidney disease has increased significantly in recent years.’
    • ‘Panchayats should take the initiative to reduce the incidence of the disease at grass-root levels.’
    • ‘The incidence of various diseases, including cancer, increases with age.’
    • ‘The incidence of crime in most categories has increased in Co Mayo.’
    • ‘The authors also cautioned that low infant mortality and longer life expectancy tend to increase the incidence and prevalence of cancer.’
    • ‘Food irradiation, it argues, reduces the incidence of food-borne diseases.’
    • ‘We estimated relative risks with rate ratios comparing the incidence of stroke in a particular fifth of dietary intake with that of the lowest fifth.’
    • ‘Trees can help reduce the incidence of respiratory diseases as well as lung cancer.’
    • ‘There are different skull shapes, different frequencies of blood types, different incidences of heritable diseases.’
    • ‘Prostate cancer has the highest incidence rate among men, and it gets a lot of attention from the media too.’
    occurrence, prevalence, commonness
    View synonyms
    1. 1.1 The way in which the burden of a tax falls upon the population.
      ‘the entire incidence falls on the workers’
      • ‘Answers to these questions involve the incidence of taxation and, therefore, its distribution.’
      • ‘It is commercial to take into account the possible incidence of double taxation in jurisdictions outside Australia.’
      • ‘In practice, the eventual receipts of any party will be reduced by the incidence of income tax.’
      • ‘For example, he treated the incidences of taxes on capital and land in lieu of examining the effects of a property tax per se.’
      • ‘Tax incidence is clearly an important issue - where does the burden really fall?’
  • 2Physics
    The intersection of a line, or something moving in a straight line, such as a beam of light, with a surface.

    • ‘Due to the glancing incidence of the ion beam, argon is not implanted into the sample surface.’
    • ‘The optical output to which a given beam travels depends on the beam's respective direction of incidence.’
    • ‘With grazing incidence diffraction a monoclinic tilted chain lattice is found in the condensed phase.’


Incidence and incidents sound the same, but incidence is more often used in technical contexts, referring to the frequency with which something occurs: increased ultraviolet light is likely to cause increased incidence of skin cancer. Incidents is simply the plural of incident, an event: the police are supposed to investigate any incidents of domestic violence. The form incidences should be avoided


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.