unidirection

From uni- +‎ direction.

unidirection (uncountable)

1. The property of being unidirectional.
   • 1991, John Jacob Ballenger, Diseases of the Nose, Throat, Ear, Head, and Neck, page 780:

     The use of a fiber to deliver the laser energy to tissue caused the laser beam to lose its collimation (unidirection).