Adjectives: rules for forming comparatives and superlatives

The rules for forming comparatives and superlatives from adjectives are varied.

 

Comparatives of Adjectives

Examples:

Misty Blue is a stronger horse on the flat.
("stronger": comparative of strong)

The band must be made from a more precious metal than silver.
("more precious": comparative of precious)

Peter is far clumsier.
("clumsier": comparative of clumsy)

Try this question. It is less difficult.
("Less difficult" is a comparative of difficult. However, it is common practice to
choose a word with the opposite meaning rather than use the 'less' form.
(e.g., less difficult = easier / less strong = weaker)

The pansies here seem less dainty than the ones at home.
("less dainty": comparative of dainty)

 

Superlatives of Adjectives

Geoff is now officially the strongest man in the world.
("strongest": superlative of strong)

The bill is extortionate, and this is the noisiest place I have ever stayed.
("noisiest": superlative of noisy)

It is the least attractive offer, but we are obliged to take it.
("least attractive": superlative of attractive)

He ranks as one of the most silly people on the planet.
("silliest": superlative of silly)

Last week, I stated that this woman was the ugliest woman I had ever seen. I have since been visited by her sister and now wish to withdraw that statement. (Mark Twain)
("ugliest": superlative of ugly)

NOTE:

Words like "prettier" and "richer" (formed from the adjectives "pretty" and "rich") are known as comparatives. A comparative is used to show who (or what) has a quality to the greater or lesser degree. (In the first example below, the quality being compared is height.)
You call that high? Blackpool Tower is higher.
("higher": comparative of "high")
The male fish is more beautiful than the female.
 ("more beautiful": comparative of "beautiful")

SUPERLATIVE?

Words like "prettiest" and "richest" (formed from the adjectives "pretty" and "rich") are known as superlatives. A superlative is used to show who (or what) has a quality to the greatest or least degree.
It is the most wonderful chocolate fudge I have ever tasted.
("most wonderful": superlative of "wonderful")
Adam is good, but Simon is the best.
("best": superlative of "good")

BEWARE:

ONLY DO IT ONCE

When forming a comparative or a superlative, be careful not to use a double comparative or a double superlative. This is a common mistake, particularly in speech.
Ann is more prettier than Carla.
(This is a double comparative. The word "prettier" is the comparative of pretty. It is a mistake to use the word
"more" as well.)
Ann is prettier than Carla.
He was the most best player.
(This is a double superlative. The word "best" is the superlative of good. It is a mistake to use "most" as well. The word 'bestest' is obviously wrong too.)
He was the best player.
Geoff was most quickest in the
trials.

MORE SINGLE? 

Arguably, there are adjectives that should not have comparative or superlative forms, because their meanings already express the qualities to the highest possible degree. For example:
'instantaneous' (< Can something be more instantaneous?)

Other examples are: single, unique and dead.