RhymeZone: shortwave definitions

Definitions of shortwave:

adjective: (of radio waves) Having a wavelength of approximately 10 to 100 meters.
adjective: (of radio equipment) Capable of transmitting or receiving signals at such a wavelength.
noun: An electromagnetic wave having a wavelength between approximately 10 and 100 meters, corresponding to frequencies between 3 and 30 MHz.
noun: (colloquial, usually in the plural) Any frequency in this range, especially when used in broadcasting.

(Definitions from Wiktionary)