1. See upright. 1. horizontal. 1  being in a position or direction perpendicular to the plane of the horizon; upright; plumb. 2  of, pertaining to, or situated at the vertex. 3  Anatomyof or pertaining to the cranial vertex.
Last Updated: Radio wave, wave from the portion of the electromagnetic spectrum at lower frequencies than microwaves. The wavelengths of radio waves range from thousands of metres to 30 cm. These correspond to frequencies as low as 3 Hz and as high as 1 gigahertz (109 Hz).
Radio waves is the type of electromagnetic wave that has the greastest wave length. 7 people found this useful. Edit. Share to: 1  The Theories and Inventions of Christiaan Huygens Christiaan Huygens is best known for his wave theory of light. 2  He was also a skilled lens maker and a builder of telescopes.