Definition of R0 in English:

R0

(also R-naught, R-zero)

Pronunciation /ˌärˈnôt/ /ˌɑrˈnɔt/ /ˌärˈzirō/ /ˌɑrˈzɪroʊ/

noun

Medicine
  • A figure expressing the average number of cases of an infectious disease arising by transmission from a single infected individual, in a population that has not previously encountered the disease.

    • ‘early estimates by the World Health Organization suggest an R0 of between 1.4 and 2.5’

Origin

1980s from the initial letter of reproduction or reproductive + 0.