Adjective

Few moments in English history have been more hungry for the future, its mercurial possibilities and its hope of richness, than the spring of 1603. — Adam Nicolson , God's Secretaries ,

Though you could see all three places in one day, each of them makes you want to stay or to keep returning to watch the effects of the changing weather and the mercurial Sicilian light. — Francine Prose , Atlantic ,

Some scientists suggest that because manic-depressive patients are ever riding the bio-chemical express between emotional extremes, their brains end up more complexly wired and remain more persistently plastic than do the brains of less mercurial sorts. — Natalie Angier , New York Times ,

Still grinning, still miming, he samba-ed across the floor … and started in on the dishes with a vigor that would have prostrated his mercurial cousin. — T. Coraghessan Boyle , Harper's ,

the boss's mood is so mercurial that we never know how he's going to react to anything