| SIAD | Self Injury Awareness Day 
| Others |
| SIAD | Shanghai International Autocity Development
| Others |
| SIAD | Short Interval Additional Dose
| Others |
| SIAD | Sierra Army Depot
| Others |
| SIAD | Smart Integrated Access Device
| Others |
| SIAD | Societa Italiana Automobili Darracq
| Others |
| SIAD | Society of Illustrators Artists and Designers
| Others |
| SIAD | Society of Illustrators, Artists, & Designers
| Others |
| SIAD | Society of Industrial Artists and Designers
| Others |
| SIAD | Statistical Information Analysis Division
| Others |
| SIAD | Statistical Information Analysis Division (DOD)
| Others |
| SIAD | Stop islamiseringen af Danmark
| Others |
| SIAD | Supersonic Inflatable Aerodynamic Decelerator
| Others |
| SIAD | Surrey Institute of Art and Design, University College, UK
| Others |
| SIAD | Sustainable Integrated Area Development
| Others |
| SIAD | Synergistic Isogenous Activated Decontamination
| Others |