A superlative adjective expresses the extreme or highest degree of a quality. We use a superlative adjective to describe the extreme quality of one thing in a group of things.

We can use superlative adjectives when talking about three or more things (not two things).

In the example below, "biggest" is the superlative form of the adjective "big":

A   B   C
A is the biggest.

As with comparative adjectives, there are two ways to form a superlative adjective:

We also usually add 'the' at the beginning.

2-syllable adjectives ending in -y happy, easy
RULE: add "-est" old → the oldest
Variation: if the adjective ends in -e, just add -st late → the latest
Variation: if the adjective ends in consonant, vowel, consonant, double the last consonant big → the biggest
Variation: if the adjective ends in -y, change the y to i happy → the happiest
2-syllable adjectives not ending in -y modern, pleasant
all adjectives of 3 or more syllables expensive, intellectual
RULE: use "most" modern → the most modern
expensive → the most expensive
With some 2-syllable adjectives, we can use "-est" OR "most":

quiet → the quietest/most quiet
clever → the cleverest/most clever
narrow → the narrowest/most narrow
simple → the simplest/most simple

Exception: The following adjectives have irregular forms:

• good → the best
• far → the farthest/furthest

We use a superlative adjective to describe one thing in a group of three or more things. Look at these examples:

• John is 1m75. David is 1m80. Chris is 1m85. Chris is the tallest.
• Canada, China and Russia are big countries. But Russia is the biggest.
• Mount Everest is the highest mountain in the world.

If we talk about the three planets Earth, Mars and Jupiter, we can use superlative adjectives as shown in the table below:

Earth Mars Jupiter
Diameter (km) 12,760 6,790 142,800 Jupiter is the biggest.
Distance from Sun (million km) 150 228 778 Jupiter is the most distant from the Sun.
Length of day (hours) 24 25 10 Jupiter has the shortest day.
Moons 1 2 16 Jupiter has the most moons.
Surface temp. (degrees Celsius) 22 -23 -150 Jupiter is the coldest.
When we compare one thing with itself, we do not use "the":

England is coldest in winter. (not the coldest)

My boss is most generous when we get a big order. (not the most generous)