I'm not familiar with the word, but the comparative form of multi-syllabic adjectives is formed by adding the word "more" in front of it. The superlative form of multi-syllabic adjectives is formed by adding the word "most" in front of it.
comparative : purer superlative : purest
Comparative: older Superlative: oldest
Dative; Early Comparative; Earlier Superlative; Earliest
The comparative and superlativeforms of grand are: Comparative: grander Superlative: grandest
comparative - merrier superlative - merriest
Comparative: shallower Superlative: shallowest
The comparative is "stricter" and the superlative is "strictest".
comparative = sadder superlative = saddest
The comparative is greater and the superlative is greatest.
Comparative: Whiter Superlative: Whitest
The comparative is grumpier and the superlative is grumpiest.
Comparative: unrulier Superlative: unruliest