Office of Technology Assessment 
Optical Telescope Assembly 
Operational Test Agency 
Open Test Assembly 
Operational Transconductance Amplifier 
Office of Technical Assistance 
Office of Temporary Assistance 
Operation-Triggered Architecture 
Or there about 
Oracle Training Administration 
Orascom Telecom of Algeria 
over the air 
Over-The-Air activation of services 
Objective Technical Architecture 
Occupational Therapist Assistant 
occupational therapy assistant 
ochratoxin A 
Off The Air 
Office of Technology Applications 
Office of Technology Assistant 
Office of Terrorism Analysis 
Office of Transportation Audits 
Official Test Aerosol 
Ohio Telephone Association 
Oil Sump Temperature APU 
Oklahoma Telephone Association 
Oklahoma Trucking Association 
oligo-terato-asthenozoospermia 
Omaha Transit Authority 
Ontario Trucking Association