****** OF Overflow Flag
***** OF Operand Fetch (Von Neumann cycle step)
***** OF Ordem dos Farmacêuticos (Portuguese Pharmaceutical Society)
**** OF Osvobodilna Fronta
*** OF Osseointegration Foundation
** OF One Fitness Sdn. Bhd (Johor Bahru, Johor, Malaysia)
* OF Open Firmware
* OF Object Finance
* OF Objective Force (US Army)
* OF Obstacle Free
* OF Oil Fired
* OF Old Face
* OF Old Fart
* OF Old French
* OF Olivier Fraysse
* OF Outfield (Baseball, Softball)
* OF Outfielder
* OF Outfitting
* OF OutFront (web development help site and forum community)
* OF Output File (Linux command line)
* OF Overflow
* OF Operation Firestorm
* OF Opposing Force
* OF Optical Fiber
* OF Optical Fuse (Delaire)
* OF Optional Form
* OF Original Formulation (pharmaceutical)
* OF Overland Flow
* OF Owner's Funds (finance)
* OF Oxygen-Free