| | S/MIME | | secure Multipart Message Extension |
| | S/PDIF | | Sony/Philips Digital Interface |
| | S4S | | sign for sign |
| | S4S | | site for site |
| | S4S | | Surfaced four Sides |
| | SA-CD | | Super Audio CD |
| | SAAAOAG | | Simple As An Ass On A Goat |
| | SAAB | | Svenska Aeroplan Aktiebolaget |
| | SADT | | Structured Analysis and Design Technique |
| | SAE | | Society of Automotive Engineers |
| | SAE | | stamped addressed envelope |
| | SAF | | Single Asian Female |
| | SAFTL | | Sequential Access Flash Translation Layer |
| | SAG | | saw |
| | SAG | | Screen Actors Guild |
| | SAHD | | stay at home dad |
| | SAHH | | Stay At Home Husband |
| | sahm | | stay at home mother |
| | sahm | | stay at home mum |
| | sais | | Student Assessment of Instruction System |
| | SAMF | | Sad Ass Mother f**ker |
| | SAMFUTU | | Situation Abnormal More f**ked Up Than Usual |
| | SAMFUTU | | Situation Abnormal, More f**ked Up Than Usual |
| | SAMG | | Simple Audio Manager |
| | sans | | sense |
| | sans | | system administration networking and security |
| | SAO | | Situation, Action, Outcomes |
| | SAPFU | | Surpassing All Previous f**k Ups |
| | sar | | Search and Rescue |
| | sar | | Smart Arse Remark |
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