There are 12 words that start with 'manni'.
| manning | mannish | 
| mannite | mannikin | 
| mannites | mannitic | 
| mannitol | mannikins | 
| mannishly | mannitols | 
| mannishness | mannishnesses | 
Note: These 12 words that start with 'manni' are found from the USA & Canada version of the tournament Scrabble word list.