from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A relatively high-energy photon having a wavelength in the approximate range from 0.01 to 10 nanometers.
- n. A stream of such photons, used for their penetrating power in radiography, radiology, radiotherapy, and scientific research. Often used in the plural. Also called roentgen ray.
- n. A photograph taken with x-rays.
- transitive v. To irradiate with x-rays.
- transitive v. To photograph with x-rays.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Alternative spelling of X-ray.
From the fact that it was a previously unknown form of radiation when first discovered.(American Heritage® Dictionary of the English Language, Fourth Edition)