reflection

—reflectional, adj. —reflectionless, adj.

/ri flek"sheuhn/, n.

1. the act of reflecting or the state of being reflected.

2. an image; representation; counterpart.

3. a fixing of the thoughts on something; careful consideration.

4. a thought occurring in consideration or meditation.

5. an unfavorable remark or observation.

6. the casting of some imputation or reproach.

7. Physics, Optics.

a. the return of light, heat, sound, etc., after striking a surface.

b. something so reflected, as heat or esp. light.

8. Math.

a. (in a plane) the replacement of each point on one side of a line by the point symmetrically placed on the other side of the line.

b. (in space) the replacement of each point on one side of a plane by the symmetric point on the other side of the plane.

9. Anat. the bending or folding back of a part upon itself.

Also, esp. Brit., reflexion.

[1350-1400; ME < LL reflexion- (s. of reflexio) a bending back, equiv. to L reflex(us) (see REFLEX) + -ion- -ION]

Syn. 3. meditation, rumination, deliberation, cogitation, study, thinking. 5. imputation, aspersion, reproach, criticism.

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Change in the direction of propagation of a wave that strikes a boundary between different media through which it cannot pass.

When a wave strikes such a boundary it bounces back, or is reflected, just as a ball bounces off the floor. The angle of incidence is the angle between the path of the wave and a line perpendicular to the boundary. The angle of reflection is the angle between the same line and the path of the reflected wave. All reflected waves obey the law of reflection, which states that the angle of reflection is equal to the angle of incidence. The reflectivity of a material is the fraction of energy of the oncoming wave that is reflected by it.

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▪ physics

      abrupt change in the direction of propagation of a wave that strikes the boundary between different mediums. At least part of the oncoming wave disturbance remains in the same medium. Regular reflection, which follows a simple law, occurs at plane boundaries. The angle between the direction of motion of the oncoming wave and a perpendicular to the reflecting surface (angle of incidence) is equal to the angle between the direction of motion of the reflected wave and a perpendicular (angle of reflection). Reflection at rough, or irregular, boundaries is diffuse. The reflectivity of a surface material is the fraction of energy of the oncoming wave that is reflected by it. See also total internal reflection.

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