There are 9 words that start with 'raref'.
| rarefy | rarefied | 
| rarefier | rarefies | 
| rarefiers | rarefying | 
| rarefaction | rarefactions | 
| rarefactional | |
Note: These 9 words that start with 'raref' are found from the USA & Canada version of the tournament Scrabble word list.