Objective Evidence: Information that can be proved true, based on facts obtained through observation, measurement, tests or other means.

OHM: A unit of electrical resistance equal to the resistance between two points on a conductor when a potential difference of one volt between them produces a current of one ampere.

OHMmeter: A instrument for measuring resistance.

Optical Pyrometer: An instrument designed to estimate the temperature of glowing surfaces.

Optical Tooling: The geometric method of optically establishing a precise line and/or reference plane.

Organization: Company, corporation, firm, enterprise, or institution or part, thereof, whether incorporated or not, public or private, that has its own functions and administration.

Organizational Structure: Responsibilities, authorities, and relationships, arranges in a pattern, through which an organization performs its functions.

Out of Phase: Having waveforms that are of the same frequency but not passing through corresponding values at the same instants.

Out-of-Round: The high and low spots in a true circle.

Overshoot: The initial transient response to an unidirectional change in input which exceeds the steady stat response.