open slating - overheating
- optical spectrograph
- optical square
- optical square method
- optical thread caliper
- optically flawless glass
- optics
- optimal
- optimal choice
- optimization
- optimization of design
- optimum moisture content
- optimum peopling
- optimum speed
- optimum water content
- option
- optional
- optional cargo
- optional relay
- opus quadratum
- opus reticulatum