O/P Out of print

O/T Overtime

O4S Objects for Systems

OA Office Administrator

OAEP Optimal Asymmetric Encryption Padding

OAO Over And Out

OAOO One And Only One

OASrN On a site right now

OATUS On A Totally Unrelated Subject

OAUS On A Unrelated Subject

OBE Order of the British Empire

OBEX Object Exchange

OBICU Obstetric Intensive Care Unit

OBKB Okay, bye bye

OBO Or Best Offer

OBTWIAU Oh by the way I adore you

OC Operations Centre

OCD Obsessive compulsive disorder

OCIA Of Course I Am

OCONUS Outside Continental United States

OCR Official cash rate
OCR Optical Character Recognition

OD Oh dear
OD Overdose
OD Overdraft

ODBC Open DataBase Connectivity

ODI One Day International

ODL Oh Dear Lord

ODMA Open Document Management API

ODPM Office Of the Deputy Prime Minister

OE Original Equipment
OE Overseas Experience

OECD Organisation for Economic Co-operation and Development

OEM Oringinal equipment manufacturer

OFDM Orthogonal Frequency Division Multiplexing

OFS One Finger Salute

OFTEL Office of Telecommunications

OGC Office of Government Commerce

OGKT Only God Knows That

OGTDA One good turn deserves another

OH&S Occupational Health and Safety

OHDH Old Habits Die Hard

OHOTKOHOTC One Hand On The Keys, One Hand On The Crotch

OHV OverHead Valve

OHW On Her Way
OHW On His Way

OIC Oh, I see

OICU812 Oh, I See You Ate One Too

OICURMT Oh, I see you are empty

OIS Oh I see

OIU Operator Interface Unit

OJ Only Joking
OJ Orange Juice

OJT On the job training

OKBB OKay, Bye Bye

OLAP Online Analytical Processing

OLED Organic Light Emitting Diode
OLED Organic Light Emitting Display

OLF One Line Followup

OLL OnLine Love
OLL Only laughing a little

OLTP On Line Transaction Processing

OMA Only Mildly Amusing

OMAC One Man Army Corps

OMB On My Butt

OMBLMAF On My Butt Laughing My Arse Off

OMFUG Other Music for Urban Gourmets

OMG Oh my God

OMHO Only my humble opinion

OMIK Open mouth insert keyboard

OMKC On My Knees Crying

OMM On My Monitor

OMMIAMP One Mans Meat Is Another Mans Poision

OMP Operational Maximum Power

OMT One more time

OMW On my way

ONNA Oh no not again
ONNA Oh No, Not Again
ONNA Oh No, Not Again !

ONNTA Oh No Not This Again
ONNTA Oh No, Not This Again

ONO Or near offer

ONOH On the Other Hand

ONS One Night Stand

ONTFLMAO On the floor laughing my ass off

OO2U Option Open to You

OOAD Object Oriented Analysis and Design

OOAK One Of A Kind

OOE Out of endurance

OOF Out Of the Office

OOH On one hand

OOI Out of interest

OOIE Object-Oriented Information Engineering

OOL Out Of Line
OOL Out Of Luck

OOMPR Out Of My Price Range

OOO Out of office
OOO Out Of Order
OOO Surprised

OOP Object Oriented Programming
OOP Out of power
OOP Out Of Print

OOSOM Out Of Sight Out Of Mind

OOT Object-Oriented Technology
OOT Out Of Touch
OOT Out Of Town

OOTC Obligatory On Topic Comment

OOTD One Of These Days

OOTO Out Of The Ofice

OOTQ Out Of The Question

OOTW Out Of This World

OPAC Online Public Access Catalogues

OPD Obnoxious Personality Disorder

OPEC Organization of Petroleum Exporting Countries

OPL Obvious Panty Line

OPM Other People's Money

OPP Other People's Problems

ORV Off Road Vehicle

OS Operating system

OSD Object Based Storage Device
OSD Object Storage Device

OSEK Open systems and the Corresponding Interfaces for Automotive Electronics

OSH Occupational Safety and Health Administration

OSHA Occupational Safety and Health Administration

OSIM Oh Shoot It's Monday

OSU Officially Sanctioned User

OT1H On The One Hand

OTA Or there about
OTA Over the air

OTAOK Over the air OK

OTB Off To Bed
OTB On-The-air Bitmap

OTBE Over Taken By Event

OTC Over the counter

OTD Out The Door

OTDOA Observed Time Difference of Arrival

OTE Off Track Excursion
OTE Off Track Experience
OTE Operational test and evaluation
OTE Operator training equipment
OTE Over the edge

OTFS Office of Treasury and Fiscal Services

OTGH On The Gripping Hand

OTJ On The Job

OTK Over The Knee
OTK Over the knuckle

OTL Out to Lunch

OTMH Off the top of my head

OTMs Other Than Mexicans

OTO Over-stating the obvious

OTOH On the other hand

OTOOH On The Other Other Hand

OTP On the phone
OTP One Time Password

OTR On the road

OTS Off The Shelf
OTS Officer Training School

OTTH On The Third Hand

OTTOMHAROO Off the Top of My Head and Rolling Out of Bounds

OUAT Once Upon A Time

OUSU Oh, You Shut Up

OVAs Original Video Animations

ow Oh Well
ow Other Woman

OW2TE Or Words To That Effect

OWASP Open Web Application Security Project

OWFM Often Works For Me

OWL-S Web Ontology Language for Services

OWP Ordinary waiting period

OYMSYP Open your mouth, solve your problem