| S2W | Scan to Web 
| Others |
| S2W | Share to Web
| Others |
| S3 | Seaman 3rd Class
| Others |
| S3 | Simple Storage Service
| Cloud Computing, AWS |
| S3&K | Sonic 3 & Knuckles (Sonic 3 and Sonic & Knuckles combination)
| Others |
| S38 | Senate Bill 38
| Others |
| S3C | Spa Classic Car Club
| Others |
| S3E | Scramble three eggs
| Others |
| S3E | Simplified Self Service Enterprise
| Others |
| S3G | S3 Graphics
| Others |
| S3I | Sample file (Digiplayer - ST3)
| Others |
| S3I | Signatures, Sensors, and Signal Processing Integration
| Others |
| S3ID | Society of the 3rd Infantry Division
| Others |
| S3IDSF | Society of the 3rd Infantry Division Scholarship Foundation
| Others |
| S3M | Scream Tracker III 16-channel Music file
| Others |
| S3M | Software Support and System Management
| Others |
| S3SB | Audi S3 Sportback
| Others |
| S3T | Sequentially Sampling Sediment Trap
| Others |
| S3TC | S3 Texture Compression
| Others |
| S4 | STANDS4
| Others |
| S4B | Skype for Business
| Others |
| S4BH | Standards for Better Health
| Others |
| S4BOT | Stands4 Bot
| Others |
| S4C | Stand For Children
| Others |
| S4D | Space4Development
| Others |
| S4D | Speak for the Dead
| Others |
| S4D | Sports for Development
| Others |
| S4E | Search For Enlightenment
| Others |
| S4E | Small Conventional Cab 4wd Extended
| Others |
| S4E4 | Season 4 Episode 4
| Others |
| S4HC | Solutions for Human Capital, Inc.
| Others |
| S4L | Silhouette 4wd Luxury
| Others |
| S4L | Sisters For Life
| Others |
| S4N | Single For Now
| Others |
| S4N | STANDS4 Network.
| Others |
| S4S | Sh*t 4chan Says
| Others |
| S4S | Share for Share
| Others |
| S4S | Shoutout for Shoutout
| Others |
| S4SD | Strive for a Safer Drive
| Others |
| S4U | Service for User
| Others |
| S4WD | Selectable Four Wheel Drive
| Others |
| S4Y | Service4You
| Others |
| S5D | Society of the 5th Division
| Others |
| S5GTT | Supercinq Gt Turbo
| Others |
| S5SB | Audi S5 Sportback
| Others |
| S6E | Straight Six Engine
| Others |
| S6M | Straight Six Mafia
| Others |
| S7 | Secondary 7
| Others |
| S7SB | Audi S7 Sportback
| Others |
| S8 | Sate
| Others |