1. (

• erratic ,
• fickle ,
• mercurial ,
• quicksilver

) 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" ;

2. (

• Mercurial ,

) relating to or under the (astrological) influence of the planet Mercury; "the Mercurial canals" ;

3. (

• Mercurial ,

) relating to or having characteristics (eloquence, shrewdness, swiftness, thievishness) attributed to the god Mercury; "more than Mercurial thievishness" ;

4. (

• mercurial

) relating to or containing or caused by mercury; "mercurial preparations"; "mercurial sore mouth" ;