• ADD, National Rail station code for Adderley Park railway station, United Kingdom
• ADD, IATA airport code for Bole International Airport in Addis Ababa, Ethiopia^[1]
• ADD, SPARS code appearing on some compact disc recordings, telling the consumer that the recording was made on analog (A) equipment and digital (D) equipment was used to mix/edit and master the recording
• ADD, accumulated degree days as calculated by summing average daily temperatures and used to determine the state of temperature dependent processes, usually biological
• ADD, Arab Digital Distribution, a pay television network in the Middle East and North Africa
• ADD, architectural design document, describes the architectural design using the software requirements and the logical model defined in the software design document (SDD)

• ADD, automatic dropping device, equipment of rail vehicle pantograph preventing further damage to vehicle or infrastructure by automatically lowering the pantograph in case of damage to carbon strip^[2]
• ADD model, a hypothesis in physics to explain the weakness of gravity relative to the other forces
• ADD, attention deficit disorder, also referred to as ADHD, Adult ADHD, and Adult ADD
• "A.D.D", a song on Vanilla Ice's third studio album "Hard to Swallow."
• ADD2, advanced digital display 2), a designation for Intel SDVO adapter cards

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