| FIR | the quality of being steady or securely and immovably fixed in place |
|---|---|
| FIR | the trait of being resolute |
| FIR | the property of being unyielding to the touch |
| FIR | the firmness and tone of healthy tissue |
| FIR | (computer science) coded instructions that are stored permanently in read-only memory |
| FIR | the fielding position of the player on a baseball team who is stationed at first base |
| FIR | the lowest forward gear ratio in the gear box of a motor vehicle |
| FIR | (Great Britain) an honours degree of the highest class |
| FIR | the first element in a countable series |
| FIR | the first or highest in an ordering or series |
| FIR | the time at which something begins |
| FIR | being the gear producing the lowest drive speed |