Adjectives have inflections. That is, adjectives change in spelling according to how they are used in a sentence. Adjectives have three forms: positive, comparative, and superlative.
The simplest form of the adjective is its positive form. When two objects or persons are being compared, the comparative form of the adjective is used. When three or more things are being compared, we use the adjective’s superlative form.
A few adjectives, like good and bad form their comparatives with different words: That is a good book. This is a better book. Which of the three is the best book? He made a bad choice. She made a worse choice. They made the worst choice of all.
The comparative forms of most adjectives, however, are formed by adding the suffixes -er and -est, or by placing the words more and most in front of the positive form.
RULES FOR FORMING COMPARATIVES:
1. One syllable words form the comparative by adding -er and -est:
brave, braver, bravest
small, smaller, smallest
dark, darker, darkest.
2. Two-syllable words that end in -y, -le, and -er form the comparative by adding -er and -est:
pretty, prettier, prettiest
happy, happier, happiest
noble, nobler, noblest
clever, cleverer, cleverest
3. Words of more than two syllables form the comparative with more and most:
beautiful, more beautiful, most beautiful.
resonant, more resonant, most resonant
4. Past participles used as adjectives form the comparative with more and most:
crooked, broken, damaged, defeated, etc.
5. Predicate adjectives (adjectives used to describe the subject of a sentence) form the comparative with more and most:
afraid, mute, certain, alone, silent, etc.
Ex. She is afraid. He is more afraid. They are the most afraid of them all.
So far, so good, but when it comes to two-syllable words other than the ones covered by Rule 2, the writer must consider custom and ease of pronunciation. Usually, two syllable words that have the accent on the first syllable form the comparative by adding -er and -est.
Ex. common, cruel, pleasant, quiet.
BUT tasteless, more tasteless, most tasteless. Some two-syllable words that have the accent on the second syllable form the comparative by adding -er and -est: polite, profound, BUT: bizarre, more bizarre, most bizarre..