American Heritage Dictionary
(6)
Century Dictionary
(12)
GNU Webster's 1913
(2)
WordNet
(4)
Elsewhere on the web
Talor Battle, Penn State's mercurial guard - mercurial is a great word, isn't it?
Kitt embodied a somewhat dated aspect of womanhood: mysterious, mercurial, and malevolent, a strange collision of muse and minx.— Dusty Wright's Culture Catch - Smart, Pop Culture Podcasts & Written Reviews - Arts & Entertainment

American Heritage Dictionary (1)
Century Dictionary (1)
Bubble size: how much this word was used in a year
Bubble height: used more or less than expected, vs. all uses evenly distributed
You can expect to see this word about once a month.