Incidence
Incidence , noun
[Compare French incidence.]
1.
A falling on or upon; an incident; an event; an occurrence. [Obsolete] — Bp. Hall
2.
(Physics) The direction in which a body, or a ray of light or heat, falls on any surface.
In equal incidences there is a considerable inequality of refractions.
3.
The rate or ratio at which something occurs; as, the incidence of murder in Los Angeles; the incidence of cancer in men over 50.
Collocations (2)
Angle of incidence , the angle which a ray of light, or the line of incidence of a body, falling on any surface, makes with a perpendicular to that surface; also formerly, the complement of this angle.
Line of incidence , the line in the direction of which a surface is struck by a body, ray of light, and the like.