| Abbreviation | Definition |
|---|---|
| APEO | Association of Professional Engineers of Ontario |
| APHA | American Public Health Association |
| APHC | Association of Plumbing Heating Contractors |
| APRC | Alliance for Patriotic Reorientation and Construction |
| APRCP | Alliance for Patriotic Reorientation and Construction Party |
| APWA | American Public Works Association |
| AQC | Alliance for Quality Construction |
| AQCS | Andres Quality Construction Solutions |
| AQMD | Air Quality Management District |
| AR | Aluminum Roofing |
| AR | Approved Roofing |
| Ar. | Architect |
| ARO | Abrasion Resistant Overlay |
| ARO | Abrasion Resistant Overlay (Pipeline Coating) |
| ARS | Agricultural Research Service |
| ARSE | Analysis and Reconstruction Sound Engine |
| ASC | Asphalt Surface Course |
| ASC | Associated Schools of Construction |
| ASCE | Amalgamated Society of Construction Engineers |
| ASE | Alliance to Save Energy |