| S/D/W/H/o | Son/Daughter/Wife/Husband of✓ Verified | Document, Banking, Legal |
| S3 | Simple Storage Service✓ Verified | Cloud Computing, AWS |
| SABIC | Saudi Basic Industries Corporation✓ Verified | Company |
| SARS | Severe Acute Respiratory Syndrome✓ Verified | Disease |
| SCALP | Système de Croisière Autonome à Longue Portée✓ Verified | Military, Air Force, Army, Defence, Navy, Weapon |
| SCGC | Southeastern Color Guard Circuit✓ Verified | Competition, Organization, Sports |
| SCI-FI | Science Fiction✓ Verified | Genre, Literature, Movie, TV Series |
| SDMC | South Delhi Municipal Corporation✓ Verified | Municipal Corporation |
| SDR | Sales Development Representative✓ Verified | Designation / Rank, Sales |
| SEC | Securities and Exchange Commission (United States)✓ Verified | Stocks and Trading, Organization |
| SEC | Security✓ Verified | Slang, Security |
| SECI | Solar Energy Corporation of India✓ Verified | Company, Renewable |
| Selfie | Self Portrait✓ Verified | Digital Culture, Internet, Photography, Slang, Social Media |
| SHAPE | Society of Health and Physical Educators✓ Verified | Association, Education, Health, Fitness |
| SHG | Self Help Group✓ Verified | Group |
| SIA | SatCom Industry Association✓ Verified | Association, Organization, Space, Technology, Satellite Technology |
| SIA | State Investigation Agency✓ Verified | Agency, Intelligence Agency, Military, Police, Law Enforcement |
| SIP | Systematic Investment Plan✓ Verified | Finance, Investment, Stocks and Trading |
| Sitcom | Situation Comedy✓ Verified | Genre, Movie, TV Series |
| SK | Saskatchewan✓ Verified | State, Geography, Territory |
| SL | Sleeper Class✓ Verified | Transport, Railways, Travel |
| SLAC | Stanford Linear Accelerator Center✓ Verified | Research Center |
| SMB | Server Message Block✓ Verified | Computer Programming, Technology |
| SMB | Small and Medium Business✓ Verified | Business |
| SMOG | Smoke and Fog✓ Verified | Environment, Pollution |
| SNORPP | Systemic Negation of Repetitive Procedural Practice✓ Verified | Military, Movie, Quotes, Slang |
| SSBN | Ship, Submersible, Ballistic, Nuclear✓ Verified | Military, Defence, Marine Corps, Navy, Weapon, Transport, Water Transport, Submarine |
| SSL | Secure Sockets Layer✓ Verified | Internet, Networking, Security |
| STEP | Science and Technology Education Partnership✓ Verified | Education, Program |
| STEP | Standard Tool for Employment Planning✓ Verified | Business, Employment |
| SVOD | Subscription Video on Demand✓ Verified | Video Streaming |
| SWP | Systematic Withdrawal Plan✓ Verified | Finance, Investment, Stocks and Trading |