How are comparisons of adjectives formed

How are comparisons of Adjectives formed?

1. The positive degree is the simplest form of an adjective (root word). big, tall, large

2. The comparative degree of an adjective can be formed in different ways.

one-syllable adjectives

*big, red (any 3-letter-word adjective) - double the last consonant first before adding 'er.' big-bigger, red-redder

*high, great - just add 'er.' high-higher, great-greater

2-syllable adjectives (ending in 'y')

*heavy, pretty - change 'y' to 'i' first before adding 'er' ('est' to their superlative forms). heavy-heavier, pretty-prettier 

The adjective sly has two comparative forms- slyer or slier.

special cases

*active, furious - just put the word 'more' before these adjectives ('most' to their superlative forms). active-more active (not activer), furious-more furious (not furiouser)

However, an adjective such as handsome has two comparative forms: handsomer or more handsome. Both of them are considered correct.

3. The superlative degree of an adjective can be formed in different ways, too.

2 or more syllable-adjectives

*energetic, understanding - just put the word 'most' before these adjectives ('more' to their comparative forms). energetic-most energetic, understanding-most understanding

ending in 'y'

*funny, lovely  - change 'y' to 'i' first before adding 'est'. funny-funniest, lovely-lovelier

IRREGULAR ADJECTIVES - these are adjectives that change their spelling when formed to their comparative and superlative degrees.

good-better-best

bad-worse-worst

much-more-most

little-less-least

ill-worse-worst

many-more-most

far-farther-farthest

Take note of this, too.

Adjectives with absolute meanings don't have comparative nor superlative forms.

unique

perfect

exhausted

exhausting

In other words, they can't be used to compare two or more people, animals, things, places, etc. They also can't be modified by adverbs like very or so.

Therefore, don't say

I am more exhausted than you. or I am very exhausted. (Exhausted means extremely tired and having no energy.)

Any comment, suggestion or  addition that will help improve this article is very much welcome. Thank you.