incident, reflected, refracted and diffracted wave?

Answer 1

Incident: Light entering a medium, say glass, or going towards a mirror

Reflected: Incident Light reflected off the mirror at the same angle as the incident.

Refracted: Light bending towards the normal as it slows down when entering a more dense medium, eg air-glass

Diffracted: The wave spreading out, say water waves approach a small opening, they will diffract with a semi circular pattern on the other side, spreading out.

Answer 2

Angle of incidence... angle of a ray of a wave coming into a barrier (like a mirror)
Angle of reflection ..angle of a ray of a wave bouncing off a barrier. (like a mirror)
Refraction.. the bending of a wave (like light) as it passes from 1 medium (like air) into another medium (like water). This is why when you look into a pool, objects on the bottom are not exactly where you see them.
Diffraction is the scattering of a wave (like light) off of a rough surface.