terahertz radiation

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Electromagnetic radiation with waves of frequencies ranging from 0.3 × 10¹² to 3 × 10¹² hertz and of wavelengths ranging from 0.1 to 1 millimeter of potential use in detection, imaging, and communications technologies.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun engineering Electromagnetic waves with frequencies around one terahertz.
• noun engineering Especially electromagnetic waves in the range 0.1-30 THz (or subranges there of, see T-rays or T-waves).
• noun submillimeter wave radiation