A material which partially transmits light & partially scatters it:
When light passes through a transparent medium such as plain glass, it is neither reﬂected nor absorbed but totally transmitted through.  
A translucent material, on the other hand, gains its transmitted color by the resultant spectrum it transmits. As a beam of light passes through a translucent material such as glass, it can be changed by adding ﬁne particles that scatter the light giving a milky appearance.
Reference: Materials Used in Dentistry, S Mahalaxmi first ed page no  47
Reflector
Translucent
Transparent
Opaque