What is anything that refracts; specifically: (Opt.) A refracting telescope, in which the image to be viewed is formed by the refraction of light in passing through a convex lens called?

refractor — Anything that refracts; specifically: (Opt.) A refracting telescope, in which the image to be viewed is formed by the refraction of light in passing through a convex lens. (Webster's 1913.)

Sources