OR and/or or may stand for:
- In logic, the or operator that captures some of the meaning of the English conjunction "or"; see Logical disjunction.
- In electronics, the or operator is carried out by a 4071 IC
- In computer programming, or can refer to both propositional and bitwise operators in various languages
- In heraldry, Or is the tincture with the colour gold (or yellow). It is usually spelt with a capital letter to distinguish it from the conjunction.
- In the Dungeons and Dragons World of Greyhawk campaign setting, OR is an abbreviation of Oeridian Record, or Oeridian Reckoning.
- In Medicine an Operating Room.
- Old Rugbeian, a former pupil of Rugby School.
- Oregon, abbreviation for the US state.
- Oristano, abbreviation for the Italian comune.
- Oriya language (ISO 639 alpha-2, or).
- In applied mathematics, OR is an abbreviation for Operations Research, or Operational Research, the use of mathematical models, statistics and algorithms to aid in decision-making.
- In Olympic Games OR is the abbreviation for Olympic Record.
- Owasco River Railroad (reporting mark OR).
- Outdoor Research, a manufacturer of sporting equipment is also referred to as OR.
- Or (Afghanistan), a ___location in Afghanistan.
- Or (Crimea), a region in Crimea.
- Or (London), a record label which releases computer music.
- Original research, in Wikipedia jargon.
- Optima Regal, Korean car built by Kia Motors.
- Organic code in OR.
- Official Receiver.