Specular reflection
Specular reflection is the reflection of light from a surface where at the point of reflection an incident beam is reflected at (and only at) an angle equal to the angle of incidence (both taken with respect to the perpendicular at that point). Such behaviour is described by Snell's law. This is in contrast to diffuse reflection.
The most familiar example of the distinction between specular and diffuse reflection would be matte and glossy paints as used in home painting. Matte paints have a higher proportion of diffuse reflection, while gloss paints have a greater part of specular reflection.