Electromagnetic wave and X-radiation

Electromagnetic wave noun - Radiation consisting of waves of energy associated with electric and magnetic fields resulting from the acceleration of an electric charge.

X-radiation and electromagnetic wave are semantically related. In some cases you can replace phrase "X-radiation" with "Electromagnetic wave", this phrases are similar.

X-radiation noun - Electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target.

Electromagnetic wave and x-radiation are semantically related. You can use "Electromagnetic wave" instead a noun phrase "X-radiation".