| SAARC | South Asian Association for Regional Cooperation |
| SAC | Space Application Centre |
| SAFTA | South Asian Free Trade Agreement |
| SAI | Sports Authority of India |
| SAIL | Steel Authority of India Limited |
| SAPTA | South Asian Preferential Trade Arrangement |
| SARS | Severe Acute Respiratory Syndrome |
| SC | Security Council/Supreme Court |
| SCI | Shipping Corporation of India |
| SCOPE | Standing Conference of Public Enterprises |
| SCRA | Special Class Railway Apprentice |
| SCSI | Small Computer Systems Interface |
| SDR | Special Drawing Rights |
| SEBI | Securities and Exchange Board of India |
| SENSEX | Sensitivity Index (of Share Price) |
| SEZ | Special Economic Zone |
| SGPC | Siromani Gurudwara Prabandak Committee |
| SHAR | Shri Harikota Range |
| SIM | Subscriber Information Module |
| SIS | Secret Intelligence Service (U.K) |
| SITA | Suppression of Immoral Traffic in Women and Girls Act |
| SlDBI | Small Industries Development Bank of India |
| SLV | Satellite Launch Vehicle |
| SMS | Short Message Service |
| SMTP | Simple Mail Transfer Protocol |
| SPCA | Society for the Prevention of Cruelty of Animals |
| SPIC MACAY | Society for the Promotion of Indian Classical music and culture |
| SRS | Sample Registration System |
| STARS | Satellite Tracking and Ranging Station |
| STD | Subscriber Trunk Dialling; Sexually Transmitted Diseases |
| STPI | Software Technology Parks of India |
| SWAPO | South West African People's Organisation |
| TA | Traveling Allowance/Territorial Army |
| TADA | Terrorist and Disruptive Activities (Prevention) Act |
| TC | Transfer Certificate, Trusteeship Council |
| TCP | Transfer Call Protocol<br> Transmission Control Protocol |
| TELCO | Tata Engineering and Locomotive Company |
| TELEX | Tele-printer Exchange |
| TERCOM | Terrain Contour Matching |
| TFT | Thin-Film Transistor |
| TIFR | Tata Institute of Fundamental Research |
| TISCO | Tata Iron and Steel Company |
| TNT | Tri-nitro-toluene |
| TOEFL | Test of English as a Foreign Language |
| TRAI | Telecom Regulatory Authority of India |
| TRIPS | Trade Related Intellectual Property Rights |
| TTE | Traveling Ticket Examiner |
| TTFI | Table Tennis Federation of India |
| TWA | Trans World Airlines (USA) |
