accident
amount
coming to be
common occurrence
commonness
contingency
contingent
degree
event
eventuality
eventuation
extent
falling
frequence
frequency
habitualness
incident
materialization
number
occurrence
oftenness
prevalence
quantity
rate
realization
relative incidence
routineness
usualness
optical phenomenon
complication
diagnosis
duration
epidemic
epidemiology
etiology
likelihood
localization
mortality
onset
outbreak
pathogenesis
percentage
prevention
probability
progression
recurrence
relapse
risk
severity
spread
symptom
coincidence