| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| On-ni | city | Chungnam | Korea, Republic of (South) | 36.77 | 126.87 | 52 | 39240 |
| Onam-dong | city | Chungnam | Korea, Republic of (South) | 36.75 | 126.48 | 36 | 41569 |
| Onam-dong | city | Chungnam | Korea, Republic of (South) | 36.76 | 126.47 | 16 | 48112 |
| Onam-ni | city | Chungnam | Korea, Republic of (South) | 36.75 | 126.48 | 36 | 41569 |
| Onam-ni | city | Chungnam | Korea, Republic of (South) | 36.37 | 126.78 | 830 | 8144 |
| Onch'ol-li | city | Chungnam | Korea, Republic of (South) | 36.39 | 127.26 | 830 | 24986 |
| Onch'on | city | Chungnam | Korea, Republic of (South) | 36.39 | 127.26 | 830 | 24986 |
| Onch'on-dong | city | Chungnam | Korea, Republic of (South) | 36.71 | 126.18 | 29 | 5156 |
| Onch'on-dong | city | Chungnam | Korea, Republic of (South) | 36.44 | 126.80 | 830 | 7785 |
| Onch'on-ni | city | Chungnam | Korea, Republic of (South) | 36.78 | 127.02 | 39 | 75247 |
| Oncheon | city | Chungnam | Korea, Republic of (South) | 36.39 | 127.26 | 830 | 24986 |
| Onch’ŏl-li | city | Chungnam | Korea, Republic of (South) | 36.39 | 127.26 | 830 | 24986 |
| Onch’ŏn | city | Chungnam | Korea, Republic of (South) | 36.39 | 127.26 | 830 | 24986 |
| Onch’ŏn-dong | city | Chungnam | Korea, Republic of (South) | 36.71 | 126.18 | 29 | 5156 |
| Onch’ŏn-dong | city | Chungnam | Korea, Republic of (South) | 36.44 | 126.80 | 830 | 7785 |
| Onch’ŏn-ni | city | Chungnam | Korea, Republic of (South) | 36.78 | 127.02 | 39 | 75247 |
| Ongam-ni | city | Chungnam | Korea, Republic of (South) | 36.48 | 126.63 | 406 | 15489 |
| Onggijeom | city | Chungnam | Korea, Republic of (South) | 36.21 | 127.18 | 42 | 22087 |
| Ongjŏng-ni | city | Chungnam | Korea, Republic of (South) | 36.90 | 126.81 | 19 | 8136 |
| Ongnam-dong | city | Chungnam | Korea, Republic of (South) | 36.03 | 126.67 | 19 | 36412 |
| Ongnam-ni | city | Chungnam | Korea, Republic of (South) | 36.03 | 126.67 | 19 | 36412 |
| Ongnyeobong | city | Chungnam | Korea, Republic of (South) | 36.29 | 127.53 | 830 | 88866 |
| Ongnyongdong | city | Chungnam | Korea, Republic of (South) | 36.45 | 127.14 | 367 | 69811 |
| Ongsaengi-gol | city | Chungnam | Korea, Republic of (South) | 36.87 | 126.78 | 3 | 13789 |
| Onhae-ri | city | Chungnam | Korea, Republic of (South) | 36.30 | 126.75 | 239 | 9304 |
| Onham-ni | city | Chungnam | Korea, Republic of (South) | 36.35 | 126.77 | 830 | 8534 |
| Onhwae-ri | city | Chungnam | Korea, Republic of (South) | 36.30 | 126.75 | 239 | 9304 |
| Onjing-ni | city | Chungnam | Korea, Republic of (South) | 36.38 | 126.81 | 830 | 7888 |
| Onjudong | city | Chungnam | Korea, Republic of (South) | 36.76 | 127.02 | 45 | 65884 |
| Onmugi | city | Chungnam | Korea, Republic of (South) | 36.50 | 126.82 | 830 | 8356 |
| Onnamu-gol | city | Chungnam | Korea, Republic of (South) | 36.67 | 126.32 | 72 | 5573 |
| Onsen-ri | city | Chungnam | Korea, Republic of (South) | 36.78 | 127.02 | 39 | 75247 |
| Onsu | city | Chungnam | Korea, Republic of (South) | 36.30 | 126.74 | 305 | 9549 |
| Onsu-ri | city | Chungnam | Korea, Republic of (South) | 36.30 | 126.74 | 305 | 9549 |
| Onsŏk-tong | city | Chungnam | Korea, Republic of (South) | 36.80 | 126.47 | 42 | 51129 |
| Ont'am-ni | city | Chungnam | Korea, Republic of (South) | 36.35 | 126.77 | 830 | 8534 |
| Ont’am-ni | city | Chungnam | Korea, Republic of (South) | 36.35 | 126.77 | 830 | 8534 |
| Onyang | city | Chungnam | Korea, Republic of (South) | 36.78 | 127.00 | 75 | 74171 |
| Onyangmŏ-ri | city | Chungnam | Korea, Republic of (South) | 36.70 | 126.80 | 36 | 40455 |
| Onyangonch'oni-dong | city | Chungnam | Korea, Republic of (South) | 36.78 | 127.00 | 72 | 73511 |
| Onyangonch'onil-tong | city | Chungnam | Korea, Republic of (South) | 36.79 | 127.00 | 49 | 74171 |
| Onyangonch’ŏni-dong | city | Chungnam | Korea, Republic of (South) | 36.78 | 127.00 | 72 | 73511 |
| Onyangonch’ŏnil-tong | city | Chungnam | Korea, Republic of (South) | 36.79 | 127.00 | 49 | 74171 |
| Onyo | city | Chungnam | Korea, Republic of (South) | 36.78 | 127.00 | 75 | 74171 |