There are 19 words that start with 'ioni'.
| ionic | ionics | ionise |
| ionium | ionize | ionised |
| ionises | ioniums | ionized |
| ionizer | ionizes | ionicity |
| ionising | ionizers | ionizing |
| ionizable | ionicities | ionization |
| ionizations | ||
Note: These 19 words that start with 'ioni' are found from the USA & Canada version of the tournament Scrabble word list.