Incidence
来自Big Physics
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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.
wiktionary
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”).
etymonline
incidence (n.)
early 15c., "incidental matter," from Old French incidence (15c.), from Late Latin incidentia, from incidere "to happen, befall" (see incident (n.)). Meaning "act of coming into contact with or affecting" is from 1650s. In physics, of rays of light, etc., considered with reference to direction, from 1620s.
