English Grammar Book 1
consonant. With these adjectives, double the last letter
before adding er to form the comparative, and -est to
form the superlative. For example:
Comparative Superlative
big bigger biggest
dim dimmer dimmest
mad madder maddest
sad sadder saddest
4Some adjectives have two syllables and end in -y. With
these adjectives change the y to i. Then add -er to form
the comparative, and -est to form the superlative.
For example:
Comparative Superlative
busy busier busiest
dirty dirtier dirtiest