O 1215 – 1269
| 1215 | oak | 010010111111 |
| 1216 | obey | 010011000000 |
| 1217 | object | 010011000001 |
| 1218 | oblige | 010011000010 |
| 1219 | obscure | 010011000011 |
| 1220 | observe | 010011000100 |
| 1221 | obtain | 010011000101 |
| 1222 | obvious | 010011000110 |
| 1223 | occur | 010011000111 |
| 1224 | ocean | 010011001000 |
| 1225 | october | 010011001001 |
| 1226 | odor | 010011001010 |
| 1227 | off | 010011001011 |
| 1228 | offer | 010011001100 |
| 1229 | office | 010011001101 |
| 1230 | often | 010011001110 |
| 1231 | oil | 010011001111 |
| 1232 | okay | 010011010000 |
| 1233 | old | 010011010001 |
| 1234 | olive | 010011010010 |
| 1235 | olympic | 010011010011 |
| 1236 | omit | 010011010100 |
| 1237 | once | 010011010101 |
| 1238 | one | 010011010110 |
| 1239 | onion | 010011010111 |
| 1240 | online | 010011011000 |
| 1241 | only | 010011011001 |
| 1242 | open | 010011011010 |
| 1243 | opera | 010011011011 |
| 1244 | opinion | 010011011100 |
| 1245 | oppose | 010011011101 |
| 1246 | option | 010011011110 |
| 1247 | orange | 010011011111 |
| 1248 | orbit | 010011100000 |
| 1249 | orchard | 010011100001 |
| 1250 | order | 010011100010 |
| 1251 | ordinary | 010011100011 |
| 1252 | organ | 010011100100 |
| 1253 | orient | 010011100101 |
| 1254 | original | 010011100110 |
| 1255 | orphan | 010011100111 |
| 1256 | ostrich | 010011101000 |
| 1257 | other | 010011101001 |
| 1258 | outdoor | 010011101010 |
| 1259 | outer | 010011101011 |
| 1260 | output | 010011101100 |
| 1261 | outside | 010011101101 |
| 1262 | oval | 010011101110 |
| 1263 | oven | 010011101111 |
| 1264 | over | 010011110000 |
| 1265 | own | 010011110001 |
| 1266 | owner | 010011110010 |
| 1267 | oxygen | 010011110011 |
| 1268 | oyster | 010011110100 |
| 1269 | ozone | 010011110101 |
