firs - flow
- first aid set
- first class airfield
- first continuous booster phase
- first cosmic velocity
- first fire powder
- first gear torque
- first generation missile
- first ignition
- first intercept range
- first intercept zone
- first line life
- first orbit penetration system
- first order correction
- first pilot
- first run attack
- first speed
- first stage boost
- first stage burning
- first stage filter
- first stage flight
- first stage of launcher
- first stage recovery parachute
- first stage vehicle
- first strike
- first strike nuclear capability
- first strike nuclear weapon
- first strike weapon
- first surface mirror
- first use
- first use nuclear doctrine
- fish joint
- fish plate
- fish tail bit
- fishing
- fissile material
- fissile materials
- fission chain reaction
- fission explosion
- fission fusion fission explosive
- fission neutron
