gigantism

As a noun gigantism

is the quality or state of being gigantic; being of abnormally large size.

As an adjective colossal is

extremely large or on a great scale.

As nouns the difference between taxonomy and gigantism

is that taxonomy is the science or the technique used to make a classification while gigantism is the quality or state of being gigantic; being of abnormally large size.

As nouns the difference between gigantism and chiromegaly

is that gigantism is the quality or state of being gigantic; being of abnormally large size while chiromegaly is abnormal gigantism of the hands.