one- - over
- optimalizing control
- optimum life
- optimum operation
- optional equipment
- orange peel
- orange-peel defect
- orange-peel effect
- orange-red
- orange-yellow
- orbital forging
- orbital spin
- orbital-spin crystal pulling
- Orcarb process
- ord.
- order
- order (superlattice) hardening
- order hardening
- order of diffraction
- order of packing
- order of spectrum
- order-disorder phenomena
- order-disorder transformation
- order-disorder transformation temperature
- order-of-magnitude agree
- ordered region
- ordered solid solution
- ordered structure
- ordered weight
- ordered wind
- ordering
- ordinary cutting steel
- ordinary gas producer
- ordinary steel
- ordinary temperature
- ordinary tool steel
- ore
- ore addition
- ore agglomerate
- ore assaying
- ore bed