omega
omission
omnibearing
omnibearing-distance
omnidirectional
omnidistance
omnigraph
omnipole
omnirange
on
  on-axis
on-board
on-boresight
on-chip
oncoming-wave
on-course
on-demand
ondograph
ondometer
ondoscope
one

    on-axis beam

     осевой луч, аксиальный луч

     осевой пучок, аксиальный пучок