S
| "Salt horse" | Pickled beef |
| "Sand happers" | Term for South Carolina soldiers |
| "Sardine box" | Cap box |
| "Sawbones" | Surgeon |
| "Scarse as hen’s teeth" | Something rare or scarce |
| "Secesh" | A Southern sympathizer or also the Northern term for seceders |
| "Shakes" | Malaria |
| "Sham fight" | Mock battle |
| "Shebang" | A shelter tent or a pup tent |
| "Sheet iron cracker" | Term for hard tack |
| "Shin plasters" | Term for paper money |
| "Skedaddle" | To run away or leave in a hurry |
| "Skunk" | Officer |
| "Sleep tight" | Term comes from the early rope beds during the Civil War that needed to be tightened with a key to keep tight |
| "Smoked Yanks" | Union soldiers cooking over a fire |
| "Snug as a bug" | Very comfortable |
| "Soldier’s disease" | Opium addiction or withdrawl symptoms of an opium addict because opium was used in hospitals to relieve the pain |
| "Somebody’s darling" | Said of a dead body |
| "Sound on the goose" | A wealthy or well-off Southerner |
| "Sow belly" | Bacon |
| "Sparking" | Kissing |
| "Spondulix" | Money |
| "Sunday soldiers" | Insult for soldiers of little merit |
| "Sutler" | Businessmen appointed to be camp vendors, who charged inflated prices on goods |