• A and Z-DNA

• AAA protocol

• Ability, motivation and opportunity (AMO)

• Abortifacient

• Abortion

• Abstract Information Model of OGC

• Access validation mistakes

• Accomplishment verbs

• Achievement verbs

• Acreage

• Active Noise Control (ANC)

• Activity verbs

• Ad hoc workflow

• Adaptive filter

• Adaptive System

• Adaptivity

• Adenosine triphosphate (ATP)

• Administrative workflow

• ADSL

• Advertainment

• Affect idioms

• Affective Filter Hypothesis

• African American English or African American Vernacular English (AAVE)

• Agency theory

• Air dehumidification

• Air quality control

• Algorithm

• Allowables

• Alternative Vote (AV)

• Alzheimer’s dementia

• American Options

• American Petroleum Institute (API) Gravity

• Amplitude

• Analog

• Analog integrated circuits

• Anglo-Norman Period

• Anglo-Saxon Period

• Annulus

• Anticlines

• Antisocial Personality Disorder

• Apache Server Web

• Apartheid

• Appraisal Drilling

• ARPANET (Advanced Research Projects Agency Network)

• Asset allocation

• Assignment Models

• Asynchronous

• Asynchronous Network

• Asynchronous Transfer Mode (ATM)

• Asynchronous Transmission Mode (ATM)

• Attention Deficit Hyperactivity Disorder (ADHD)

• Audio Bridge

• Automatic Teller Machines (ATMs)

• Automatic Teller Terminals (ATT)

• Autopoiesis

• Axis-Shield