Adjective. Formation of Degrees of Comparison

 Similarly to nouns, adjectives change their case and number in Estonian.
Adjectives have three degrees of comparison – the positive, comparative and superlative degree. 

Comparative

The comparative is usually formed from the genitive stem of the positive degree by adding the marker -m.
noor, noore > noorem

In some two-syllable adjectives with the stem ending -a or -u, the stem vowel becomes e.
vana, vana > vanem
paks, paksu > paksem

There are some irregular adjectives, which form the comparative form from a different stem.
hea - parem
lühike - lühem
pisike - pisem  

The comparative form is declinable, and the stem ends with the vowel -a in the genitive.
raskem, raskema, raskemat

Superlative

The superlative is formed from the comparative form of the adjective by adding the adverb kõige. This form of the superlative can be formed with all adjectives.
uus; uuem > kõige uuem
rõõmus; rõõmsam > kõige rõõmsam
hea; parem > kõige parem

Like the comparative form, the superlative can be declined.