| Abbreviation | Definition |
|---|---|
| EQ | Enlisted Quarters |
| EQ | Equator |
| EQ | Equipment |
| EQN | Equation |
| ER | Earth Road |
| ER | Electro Rheological |
| ER | Electronic Reserve |
| ER | Ever Ready |
| ER | Expected Runs |
| ER | Extended Range |
| ER | Extended Response |
| ER0S | Eliminate Range Zero Situation (spelled with either letter 'O' or digit Zero) |
| ERA | Eddystone Remington Arsenal |
| ERA | Exploitation Roles Always |
| ERA | Explosive Reactive Armor |
| ERA | Extended Range Artillery |
| ERAC | Electric Armaments Research Center |
| ERADCOM | Army Electronics Research and Development Command Adelphi, MD |
| ERAM | Extended Range Active Missile |
| ERAM | Extended Range Air Munition |