mercurial >> məːˈkjʊərɪəl
Definition: [adjective] subject to sudden or unpredictable changes of mood or mind.
Example: his mercurial temperament
Definition: [adjective] of or containing the element mercury.
Example: gels containing organic mercurial compounds
Definition: [adjective] of the planet Mercury.
Definition: [noun] a drug or other compound containing mercury.
Example: for twenty years organic mercurials were the most potent diuretics in clinical use