| Acronym | Definition |
|---|
| SEC | Second(s) |
| SEC | Secretary |
| SEC | Securities & Exchange Commission (US government) |
| SEC | Section |
| SEC | Security |
| SEC | Securities and Exchange Commission (authority in the Philippines) |
| SEC | Secondary |
| SEC | Southeastern Conference |
| SEC | Secondary Containment |
| SEC | Space Environment Center (NOAA) |
| SEC | Secant (trigonometry) |
| SEC | Size Exclusion Chromatography |
| SEC | Southeastern College |
| SEC | Sun-Earth Connection (NASA) |
| SEC | Socio-Economic Classification |
| SEC | Software Engineering Center |
| SEC | Saudi Electricity Company |
| SEC | Secure Electronic Commerce |
| SEC | Sonoma Ecology Center |
| SEC | Secaucus, New Jersey (New Jersey transit) |
| SEC | South East Corner |
| SEC | Single Edge Contact (Intel) |
| SEC | Set Carry (6502 processor instruction) |
| SEC | Secretaría de Educación y Cultura (México) |
| SEC | Singapore Environment Council |
| SEC | South Equatorial Current |
| SEC | Scalable Enterprise Computing (Dell) |
| SEC | Section Executive Committee |
| SEC | Southeastern College (Pasay City, Philippines) |
| SEC | Standard Entry Class |
| SEC | Secretary's Department (International Monetary Fund) |
| SEC | Software Enabled Control |
| SEC | Samsung Electronics Corporation |
| SEC | Single Error Correction |
| SEC | Spoken English Corpus |
| SEC | Secans (trigonometry) |
| SEC | Saudi Electric Company |
| SEC | Sustainable Energy Coalition (Takoma Park, MD) |
| SEC | Surveys of Enacted Curriculum |
| SEC | Secondary Average (baseball statistic; determines how far on the bases a runner gets) |
| SEC | State Elections Commission (Puerto Rican government agency) |
| SEC | Senior Executive Council (US DoD) |
| SEC | Staphylococcal Enterotoxin C |
| SEC | Special Education Consultant |
| SEC | Single Edge Cartridge |
| SEC | SDH Equipment Clock |
| SEC | State Engineering Corporation (Pakistan government) |
| SEC | Sustainable Energy Communities |
| SEC | Seminole Electric Cooperative, Inc. |
| SEC | Société d'Entomologie du Canada |
| SEC | Social Economy Centre |
| SEC | Secondary Electron Conduction |
| SEC | Specialist Engineering Contractors Group |
| SEC | Sistema Europeo di Conti |
| SEC | Special Education Consortium |
| SEC | Society for Economic Botany |
| SEC | Software Evaluation Criteria (informatics, avionics) |
| SEC | Source Evaluation Committee |
| SEC | Spatial Error Concealment |
| SEC | Submarine Element Coordinator |
| SEC | Salvo Errore Calculi (Latin: after extensive calculations) |
| SEC | Spoiler Elevator Computer (Airbus) |
| SEC | Scientific Ethics Committee (UNESCO) |
| SEC | Shanghai Economic Commission |
| SEC | Shanghai Education Commission |
| SEC | Synchronous Equipment Clock |
| SEC | SONET/SDH Equipment Clock |
| SEC | Support Equipment Change |
| SEC | Shelf Edge Current |
| SEC | Switching Equipment Congestion signal (CCS #7/ITU-T) |
| SEC | Scientific Estimates Committee |
| SEC | Scintillator Electromagnetic Calorimeter |
| SEC | Subject Electoral Commission (Russian Federation) |
| SEC | Supreme Eiye Confraternity |
| SEC | Southern Episcopal Church |
| SEC | Service Evaluation Center |
| SEC | Self Evident Correction |
| SEC | Systems Engineering Council |
| SEC | Société d'Études Camerounaises (French) |
| SEC | Sydney Education Centre (Australia) |
| SEC | Special Support Equipment Change |
| SEC | Strategic Excellence Projects |
| SEC | Sun Energy Corporation (El Salvador) |