| A | Ampere |
| AA | Atomic absorption |
| AAF | Advanced Authoring Format |
| AAGR | Annual Average Growth Rate |
| AAS | Atomic absorption spectroscopy |
| ABC | Activity-based costing |
| ABE | Acceptor bound exciton |
| ABM | Activity-based management |
| ABS | Antilock braking system |
| Ac | Actinium |
| AC | Alternating current; Activated carbon |
| ACA | Anisotropically Conductive Adhesive |
| ACCESS | Analysis computer for component engineering services support |
| ACFA | Advanced CMOS Frame Aligner |
| ACI | After clean inspection |
| ACIA | Asynchronous Communications Interface Adapter |
| ACT | Alternative control techniques; actual cycle time |
| ADC | Analog-to-digital converter |
| ADE | Advanced development environment |
| ADI | After develop inspection |
| ADIG | Application development interface guidelines |
| ADIO | Analog/digital input/output |
| ADL | Add lot |
| ADMA | Advanced DMA controller |
| ADP | Administrative data processing |
| ADPCM | Adaptive differential pulse code modulation |
| ADR | Astra Digital Radio |
| ADSL | Asymmetric Digital Subscriber Line |
| ADT | Applied diagnostic techniques |
| ADTV | Advanced Definition TV |
| AE | Auger electron; Atomic emission; Acoustic emission |
| AEC | Advanced Equipment Controller; Architecture, Engineering and Construction |
| AECS | Automated Equipment Control System |
| AEI | After etch inspection; Automated equipment interface |
| AEM | Analytical Electron Microscopy |
| AES | Auger Electron (Emission) Spectroscopy; Advanced Encryption Standard |
| AF | Audio Frequency |
| AFC | Automatic Frequency Control; Automatic Flow Controller |
| AFD | Application framework definition |
| AFM | Atomic Force Microscopy |
| AFT | Automatic Fine Tuning |
| A-GEMTF | Advanced GEM Task Force |
| Ag | Silver |
| AGC | Automatic Gain Control |
| AGP | Accelerated Graphics Port |
| AGV | Automated guided vehicle |
| Ah | Ampere-hour |
| AHF | Anhydrous hydrogen flouride |
| AI | Artificial intelligence; Adobe Illustrator image format |
| AIS | Adhesive Interconnect System |
| Al | Aluminum |
| Al2O3 | Aluminum oxide (aka alumina or sapphire) |
| ALD | Atomic layer deposition |
| ALE | Atomic layer epitaxy; Application Logic Element |
| AlGaAs | Aluminum Gallium Arsenide |
| AlGaN | Aluminum Gallium Nitride |
| ALI | ATM Line Interface |
| ALS | Advanced light source; Advanced low-power Schottky |
| ALS | Advanced light source; Advanced low-power Schottky |
| ALT | Alternating |
| ALU | Arithmetic logic unit |
| ALVT | Advanced low voltage technology |
| Am | Americium |
| AM | Amplitude modulation; Ante meridiem (before noon) |
| AMC | Airborne molecular contamination |
| AMD | Alpha micro devices |
| AMDM | ATM Multiplexer/DeMultiplexer (QSI) |
| AMH | Automated material handling |
| AMHS | AMH Systems |
| AMI | Alternate Mark Inverse Code |
| AML | Automatic model linking |
| AMLCD | Active Matrix LCD |
| AMM | Acoustic Mismatch Model; Analog Multimeter |
| Amp | Amplifier |
| AMPS | Advanced Mobile Phone System |
| AMRAAM | Advanced Medium Range Air-to-Air Missile |
| AMT | Advanced manufacturing technology |
| AMU | Atomic mass unit |
| AND | Logic term - AND |
| ANN | Artificial Neural Network |
| ANOVA | Analysis Of Variance |
| ANPA | American Newspaper Publishers Association |
| ANSI | American National Standards Institute |
| AOI | Automatic Optical Inspection; And-Or-Invert |
| AOQL | Average Outgoing Quality Level |
| AOV | Air-Operated Valve |
| AP | Adhesion Promoter |
| APA | Advanced Performance Algorithm |
| APB | Anti Phase Boundary |
| APC | Advanced Process Control; Automatic Phase Control |
| APCD | Add-on Pollution Control Devices |
| APCFI | Advanced Process Control Framework Initiative |
| APCVD | Atmospheric Pressure Chemical Vapor Deposition |
| APD | Avalanche Photo Diode |
| APEC | Advanced Process Equipment Control |
| API | Application Programming Interface; Atmospheric Pressure Ionization |
| APIMS | Atmospheric Pressure Ionization Mass Spectroscopy |
| APM | Atmospheric Passivation Module; Acoustic Plate Mode |
| APS | American Physical Society |
| APT | Advanced Probe Technology; Automatically Programmed Tools |
| APVD | Alcatel Plasma Vapor Deposition (Alcatel-France) |
| APW | Augmented Plane Wave |
| AQI | ACCESS Query Interface |
| AQL | Acceptance Quality Level: Acceptable Quality Level |
| AQTX | Aquatic Toxicity |
| Ar | Argon |
| AR | Aspect Ratio |
| ARAMS | Automated Reliability, Availability, and Maintainability Standard |
| ARC | Antireflective Coating |
| ARCOFI | Audio Ringing Codec Filter |
| ARDE | Aspect-Ratio-Dependent Etching |
| ARIB | Association of Radio Industries and Businesses |
| ARIMA | Auto Regressive Moving Average with Integration |
| ARINC | Aeronautical Radio Incorporated |
| ARO | After Receipt of Order |
| ARPA | Advanced Research Projects Agency (formerly DARPA) |
| ARPES | Angular Resolved Photo Electron Spectroscopy |
| ARPES | Angular Resolved Photo Electron Spectroscopy |
| ARPU | Average Revenue Per User |
| ARS | Angle-Resolved Scattering |
| ARUPS | Angle-Resolved UV Photoemission Spectroscopy |
| ARXPS | Angle Resolved XPS |
| As | Arsenic |
| ASAP | Advanced Stepper Application Program |
| ASCII | American Standard Code for Information Interchange |
| ASE | Amplified Stimulated Emission |
| ASF | Windows Media Technology File Format |
| ASFU | Application Specific Full Use |
| AsH3 | Arsine |
| ASLAC | Advanced Subscriber Line Audio processing interface |
| ASLIC | Advanced Subscriber Line Interface |
| ASO | Automatic Shut-Off |
| ASP | Advanced Strip and Passivation; Advanced Strip Processor; Application Service Provider; Advanced Simple Profile |
| ASIC | Application-Specific Integrated Circuit |
| ASME | American Society for Mechanical Engineering |
| ASPaRC | Ability of Solder Paste to Retain Components |
| ASR | Automated Send Receive |
| AS/RS | Automated Storage and Retrieval System |
| ASSMBE | All Solid Source MBE |
| ASSP | Application Specific Standard Product |
| ASTM | American Society for Testing and Materials |
| ASTTL | Advanced Schottky TTL |
| ASW | Augmented Spherical Wave |
| Async | Asynchronous |
| At | Astatine |
| ATDF | Advanced Tool Development Facility |
| ATDSEM | Apply/Develop Track Specific Equipment Model |
| ATE | Automatic Test Equipment |
| ATF | Automation Test Facility (recently renamed SIL) |
| ATG | Automatic Test Generation |
| ATLAS | Abbreviated Test Language for All Systems |
| ATM | Atmosphere; Asynchronous Transfer Mode |
| ATP | Advanced Technology Program; Adenosine TriPhosphate |
| ATPG | Automatic Test Pattern Generation |
| ATR | Attenuated Total Reflectance; Air Transport Rack |
| ATR-FTIR | Attenuated total reflectance Fourier transform infrared spectroscopy |
| ATSC | Advanced Television Systems Committee |
| ATT | Attenuated |
| atto | 1.00E-18 (1/1,000,000,000,000,000,000; symbolized by the prefix a |
| Au | Gold |
| AVC | Automatic Volume Control |
| AVP | Advanced Vertical Processor |
| AVS | Advanced Visualization System |
| AVT | Accelerated Vesication Test |
| AWE | Asymptotic Waveform Evaluation |
| AWG | American Wire Gauge |
| AWGN | Additive White Gaussian Noise |
| AWS | Advanced Wet Station |