| FOS | Faint Object Spectrograph | - | Atmospheric Research Center |
| FOS | Fiber Optic Sensor | - | Computer Acronyms(common) |
| FOS | First-order Sudden | - | Computer Acronyms(common) |
| FOS | Full Of Sh*t (either Severely Constipated Or Metaphorically) | - | NASA |
| FOS | Found On Street: Unidentified Dead Homeless Person | - | NASA |
| FOS | Flight Operations Support | - | Organizations |
| FOS | Full Of Sh*t | - | ISO Country Codes |
| FOS | Family Of Systems | - | Astronomy |
| FOS | Florida Ornithological Society - Full Operational Status | - | Astronomy |
| FOS | Family Of Services | - | Business and Finance |
| FOS | Flight Operations Segment | - | Business and Finance |
