directional vs omnidirectional

directional

noun
  • Something that indicates direction, such as a vehicle's turn signal. 

adj
  • Indicating direction. 

  • Of or relating to guidance or help. 

omnidirectional

adj
  • Having a ring-shaped radiation pattern, with equal radiation in all azimuthal directions. 

  • In every direction, especially of a radio system capable of transmitting or receiving signals in all directions, or of a microphone capable of detecting sound from all directions. 

  • Of such an attack or effect that encompasses all directions. 

How often have the words directional and omnidirectional occurred in a corpus of books? (source: Google Ngram Viewer )