OA

OA, O.A., Oa, or oa may refer to:

Arts and entertainment

 * Oa (comics), a fictional planet in the DC Comics universe
 * The OA, a television series
 * OpenArena, a video game
 * Opie and Anthony (often "O&A"), a radio show
 * Oriental Adventures, a Dungeons & Dragons sourcebook
 * Orion's Arm, a science fiction project

Businesses and organisations

 * Obavještajna agencija, the Croatian Intelligence Agency
 * Office administration
 * Oficina Anticorrupción, an Argentine law enforcement agency
 * Olympic Air (IATA code OA)
 * Opera Australia, an opera company
 * Opportunitas aequa, a Canadian organization
 * Overeaters Anonymous
 * Oxford Academy (California), a high school
 * Orbital ATK, an aerospace company

People

 * Ma'am OA, nickname of Andrea Veneracion, founder of the Philippine Madrigal Singers
 * Oskar Andersson, Swedish cartoonist who uses the pen name O.A.

Places

 * Oa (Attica), a deme of ancient Attica
 * Ocean Acres, New Jersey, United States
 * Orakzai Agency, Pakistan
 * The Oa, Scotland, United Kingdom

Honors

 * Order of Australia, a formal honour
 * Order of the Arrow, the honor society of Scouting America

Science and technology

 * Office automation
 * Oleic acid, a fatty acid
 * Open access, the free online availability of digital content from scholarly sources
 * Operational amplifier, an electronic component
 * Operational analysis, more generally called "operational research", a branch of applied mathematics
 * Osteoarthritis, a disease
 * Length overall (also o/a, o.a. or oa), an abbreviation for overall, used when describing the length of a ship
 * Oxford Archaeology

Other uses

 * Oa (digraph)
 * Obituaries Australia, an online database of obituaries
 * Office Action, a communication from the U.S. Patent and Trademark Office
 * Old Alleynian, an old boy of Dulwich College
 * Old Albanian, an old boy of St Alban School, St Albans
 * Order of Appearance, a synonym for Order of battle
 * Output area, an area of approximately 100 households, derived from the UK Census