| SEP | Societe Europeenne De Propulsion | - | Atmospheric Research Center |
| SEP | Simplified Employee Pension | - | Chatting Acronyms |
| SEP | Solar Energetic Particle (event) | - | Computer Acronyms(common) |
| SEP | Standard Error Of Prediction | - | Computer Acronyms(common) |
| SEP | Stimulated Emission Pumping | - | Computer Acronyms(common) |
| SEP | Somebody Else's Problem (not To Be Confused With Sepsis) | - | NASA |
| SEP | Separation | - | Organizations |
| SEP | Source Evaluation Panel | - | Organizations |
| SEP | SUPPort Equipment Package | - | Organizations |
| SEP | Somebody Else's Problem | - | ISO Country Codes |
| SEP | Somebody Else's Problem - Spherical Error Probable - System Enhancement Package - System Engineering Plan | - | Astronomy |
