There are 21 words that start with 'rare'.
| rare | rared | 
| rarer | rares | 
| rarefy | rarely | 
| rarest | rarebit | 
| rarebits | rarefied | 
| rarefier | rarefies | 
| rareness | rareripe | 
| rarefiers | rarefying | 
| rareripes | rarenesses | 
| rarefaction | rarefactions | 
| rarefactional | |
Note: These 21 words that start with 'rare' are found from the USA & Canada version of the tournament Scrabble word list.