Transmission

Transmission means that the wave passes into the second material. The transmitted wave may change direction there: this is refraction. Passing through and bending are therefore different ideas; a refracted ray has been transmitted across the boundary.

Some of its energy may return, some may pass into the second material, and some may be taken up by the material. These effects are called reflection, transmission and absorption. A wave that passes into the second material may also be refracted.

Transmission means crossing the boundary. A transmitted ray may also refract—change direction—if its speed changes as it enters the next material. For example, light entering a glass block obliquely from air bends towards the normal.