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.
Sir I. Newton.
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.
In"ci*den*cy (?), n. Incidence. [Obs.] Shak.
In"ci*dent (?), a. [L. incidens, -entis, p. pr. & of incidere to fall
into or upon; pref. in- in, on + cadere to fall: cf. F. incident. See
Cadence.]
1. Falling or striking upon, as a ray of light upon a reflecting
surface.
2. Coming or happening accidentally; not in the usual course of things;
not in connection with the main design; not according to expectation;
casual; fortuitous.
As the ordinary course of common affairs is disposed of by general
laws, so likewise men's rarer incident necessities and utilities
should be with special equity considered.
Hooker.
3. Liable to happen; apt to occur; befalling; hence, naturally
happening or appertaining.
All chances incident to man's frail life.
Milton.
The studies incident to his profession.
Milward.
4. (Law) Dependent upon, or appertaining to, another thing, called the
principal.
Incident proposition (Logic), a proposition subordinate to another, and
introduced by who, which, whose, whom, etc.; as, Julius, whose surname
was Cæsar, overcame Pompey. I. Watts.
In"ci*dent, n. [Cf. F. incident.] 1. That which falls out or takes
place; an event; casualty; occurrence.
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2. That which happens aside from the main design; an accidental or
subordinate action or event.
No person, no incident, in a play but must be of use to carry on
the main design.
Dryden.
3. (Law) Something appertaining to, passing with, or depending on,
another, called the principal. Tomlins.
Syn. -- Circumstance; event; fact; adventure; contingency; chance;
accident; casualty. See Event.
In`ci*den"tal (?), a. Happening, as an occasional event, without
regularity; coming without design; casual; accidental; hence, not of
prime concern; subordinate; collateral; as, an incidental conversation;
an incidental occurrence; incidental expenses.
By some, religious duties . . . appear to be regarded . . . as an
incidental business.
Rogers.
Syn. -- Accidental; casual; fortuitous; contingent; chance; collateral.
See Accidental.
-- In`ci*den"tal*ly, adv. -- In`ci*den"tal*ness, n.