| Abbreviation | Definition |
|---|---|
| 0W2 | 0W2 = 0.2 Watts or 200 milliwatts (mW) |
| A | Anode |
| a | Atto (10¯¹8) |
| a | Atto (10¯¹x) |
| A | form A (normally open) contacts |
| Å | angstrom [1 x 10¯¹° meters in length] |
| Å | angstrom [1 x 10¯¹p meters in length] |
| A/D | Analog-to-Digital |
| AA | Active Active |
| AA | Anti Aliasing |
| AA | Anti-Aliasing |
| AA | Atomic Absorption |
| AA | Audio Animatronics |
| AA | Automatic Adjust |
| AAAC | All Aluminium Alloy Conductor |
| AAAC | All Aluminum Alloy Conductor |
| AAC | All Aluminium Conductor |
| AACC | Audio Active Comparative Corrective |
| AACS | Advanced Access Content System |
| AACSR | Aluminium Alloy Conductor Steel Reinforced |