opacimeter
opacity
opal
opalescence
opamp
opaque
opaqueing
opaqueness
opaquer
opcode
  open
open-air
open-bottom
opencast
open-cell
open-center
open-chain
open-channel
open-circuit
open-coil
open-conductor

    open water treatment system

    открытая система водоподготовки (для заводнения)