unidirectional
1. [ adjective ] operating or moving or allowing movement in one direction only
Examples:

"a unidirectional flow" "a unidirectional antenna" "a unidirectional approach to a problem"

Related terms: bidirectional simplex one-way unifacial one-way
Similar spelling:   undermentioned
  under_control
  underrating
  untraditional
  underproduction
  underestimation