increase or diminution of the original quality: _nice_.

The _comparative_ is that form of the adjective which expresses increase
or diminution of the quality: _nicer_.

The _superlative_ is that form which expresses the greatest increase or
diminution of the quality: _nicest_.

_or_

An adjective is in the positive form when it does not express comparison;
as, "A _rich_ man."

An adjective is in the comparative form when it expresses comparison
between two or between one and a number taken collectively, as, "John is
_richer_ than James"; "he is _richer_ than all the men in Boston."

An adjective is in the superlative form when it expresses a comparison
between one and a number of individuals taken separately; as, "John is
the _richest_ man in Boston."

Adjectives expressive of properties or circumstances which cannot be
increased have only the positive form; as, A _circular_ road; the _chief_
end; an _extreme_ measure.

Adjectives are compared in two ways, either by adding _er_ to the positive
to form the comparative and _est_ to the positive to form the superlative,
or by prefixing _more_ to the positive for the comparative and _most_ to
the positive for the superlative; as, _handsome_, _handsomer_, _handsomest_
or _handsome_, _more handsome_, _most handsome_.