F
| "Fairy fleet" | Boats carrying trade between sides at Fredericksburg |
| "Fancy girl" | Prostitute |
| "Fast trick" | Woman known for loose morals |
| "Fighting under the black flag" | Soldiers killing lice |
| "Fire and fall back" | To vomit |
| "Fit as a fiddle" | Healthy, feeling good |
| "Fit to be tied" | Angry |
| "Flux" | Diarrhea |
| "Forlorn hope" | Term for a party selected to begin an attack |
| "French leave" | AWOL |
| "Fresh Fish" | New recruit |