| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Siam | city | Ohio | United States | 41.08 | -82.88 | 948 | |
| Sicily (historical) | city | Ohio | United States | 39.03 | -83.86 | 898 | |
| Sidney | city | Ohio | United States | 40.28 | -84.16 | 948 | |
| Signal | city | Ohio | United States | 40.80 | -80.66 | 1099 | |
| Silica | city | Ohio | United States | 41.68 | -83.74 | 830 | |
| Silo | city | Ohio | United States | 41.31 | -81.28 | 1154 | |
| Siloam (historical) | city | Ohio | United States | 38.81 | -82.37 | 830 | |
| Silver Creek | city | Ohio | United States | 40.58 | -83.68 | 1076 | |
| Silver Lake | city | Ohio | United States | 41.16 | -81.45 | 1017 | |
| Silver Run | city | Ohio | United States | 38.98 | -82.09 | 830 | |
| Silver Springs | city | Ohio | United States | 39.63 | -83.87 | 997 | |
| Silver Springs | city | Ohio | United States | 40.00 | -83.15 | 941 | |
| Silverton | city | Ohio | United States | 39.19 | -84.40 | 830 | |
| Simms (historical) | city | Ohio | United States | 39.81 | -84.07 | 830 | |
| Simons | city | Ohio | United States | 41.53 | -80.53 | 1085 | |
| Simonsons (historical) | city | Ohio | United States | 39.24 | -84.79 | 830 | |
| Siney (historical) | city | Ohio | United States | 41.66 | -84.00 | 830 | |
| Sinking Spring | city | Ohio | United States | 39.07 | -83.39 | 898 | |
| Sinns Subdivision | city | Ohio | United States | 41.46 | -84.53 | 830 | |
| Sinsinatis | city | Ohio | United States | 39.16 | -84.46 | 830 | |
| Sinsinnati | city | Ohio | United States | 39.16 | -84.46 | 830 | |
| Sippo | city | Ohio | United States | 40.82 | -81.60 | 1059 | |
| Sippo Heights | city | Ohio | United States | 40.81 | -81.50 | 1095 | |
| Sites Lake Cottage Area | city | Ohio | United States | 40.78 | -82.39 | 997 | |
| Sitka | city | Ohio | United States | 39.45 | -81.34 | 830 | |
| Siverly | city | Ohio | United States | 39.35 | -82.50 | 830 | |
| Six Corners | city | Ohio | United States | 41.32 | -84.71 | 830 | |
| Six Corners | city | Ohio | United States | 41.08 | -81.42 | 1049 | |
| Six Mile | city | Ohio | United States | 39.75 | -84.31 | 997 | |
| Six Point | city | Ohio | United States | 39.72 | -81.00 | 997 | |
| Six Points | city | Ohio | United States | 41.28 | -83.55 | 830 | |
| Sixmile | city | Ohio | United States | 39.83 | -84.25 | 892 | |
| Sixteen Mile Stand | city | Ohio | United States | 39.27 | -84.33 | 830 | |
| Sixtyeight Trailer Park | city | Ohio | United States | 40.63 | -83.61 | 997 |