Adjectives recognize degrees of comparison. Nearly all adjectives have three forms: positive, comparative and superlative.

Here are some mistakes in the use of adjectives.

Double comparatives and superlatives should be avoided. Once, their use was common and acceptable in English.  However, they are no longer considered correct.

It was the most unkindest cut of all. (Shakespeare)

Incorrect: The little town had never seen a more costlier wedding.
Correct: The little town had never seen a costlier wedding.

Note that ‘lesser’ is an exception to this rule. It is a double comparative and it is often used by the best writers.

• Choose the lesser of the two evils.

The adjective preferable is often used as a comparative. Because of this reason, it is not used with ‘more’.

• In my opinion, his scheme is preferable to yours.

Note that after preferable, we use ‘to’, not ‘than’.

Less and fewer

The comparative form ‘less’ is used before uncountable nouns. ‘Fewer’ is used before countable nouns.

Note that in informal English, less is often used with plural nouns.

• Fewer than fifteen students were present in the class.
• If you want to lose weight, you should eat less fat.

Certain adjectives do not have comparative forms. These include: unique, perfect, ideal, universal, complete, entire, square, chief, extreme and round. It is wrong to say, ‘more complete’ or ‘more extreme’.