Princeton says:Webster says: (adjective)
- (liable to sudden unpredictable change) "erratic behavior"; "fickle weather"; "mercurial twists of temperament"; "a quicksilver character, cool and willful at one moment, utterly fragile the next"
- (relating to or under the (astrological) influence of the planet Mercury) "the Mercurial canals"
- (relating to or having characteristics (eloquence, shrewdness, swiftness, thievishness) attributed to the god Mercury) "more than Mercurial thievishness"
- (relating to or containing or caused by mercury) "mercurial preparations"; "mercurial sore mouth"
1: of, relating to, or born under the planet Mercury
2: having qualities of eloquence, ingenuity, or thievishness attributed to the god Mercury or to the influence of the planet Mercury
3: characterized by rapid and unpredictable changeableness of mood <a mercurial temper>
4: of, relating to, containing, or caused by mercury
a pharmaceutical or chemical containing mercury
I wonder how this relates to the element of the same name.
Mer as in merchant, summer. Cur as in cure, curious. I as in the e sound in tree, key. Al rhymes with bull.
Synonyms: (for the first Princeton definition)
erratic, fickle, quicksilver