| SO | Significant Other | - | Chemistry |
| SO | Stieltjes Orbitals (for Mol. Photoionization Continua) | - | Computer Acronyms(common) |
| SO | SuPport Operations (KSC Dir.) | - | Organizations |
| SO | FT Square Feet | - | Organizations |
| SO | Significant Other (boyfriend, Girlfriend, Wife, Husband, Partner, Spouse | - | Sms Text Smileys and Emoticons |
| SO | Significant Other (spouse, Boyfriend / Girlfriend) | - | ISO Country Codes |
| SO | Shared Object (Unix) - Sheriff's Office - Significant Other -Somalia (ISO 3166 And FIPS 10-4 Country Code Digram) | - | Astronomy |
| SO | Somali Language (ISO 639-1 Code) | - | Astronomy |
| SO | Service Order
| - | Human Genome |
