mercurial

As a noun mercurial is

(obsolete) any of the plants known as mercury.

As an adjective mercurial is

(often capitalized, see (mercurial)) pertaining to the planet mercury.

As nouns the difference between mercurial and mercurian

is that mercurial is any of the plants known as mercury while Mercurian is an inhabitant of the planet Mercury.

As adjectives the difference between mercurial and mercurian

is that mercurial is (often capitalized, see {{term|Mercurial}}) Pertaining to the planet Mercury while Mercurian is of or relating to Mercury (the planet.

As adjectives the difference between unpredictable and mercurial

is that unpredictable is unable to be predicted while mercurial is (often capitalized, see (mercurial)) pertaining to the planet mercury.

As nouns the difference between unpredictable and mercurial

is that unpredictable is an unpredictable thing while mercurial is (obsolete) any of the plants known as mercury.

As adjectives the difference between mercurial and nonmercurial

is that mercurial is (often capitalized, see (mercurial)) pertaining to the planet mercury while nonmercurial is not mercurial; not containing or relating to mercury, the chemical element.

As a noun mercurial

is (obsolete) any of the plants known as mercury.