adj.
1.liable to sudden unpredictable change
2.relating to or under the (astrological) influence of the planet Mercury
3.relating to or having characteristics (eloquence, shrewdness, swiftness, thievishness) attributed to the god Mercury
4.relating to or containing or caused by mercury
Idiom of the Day
on (someone's) shoulders
to be someone's responsibility
The responsibility for organizing the office is always on my shoulders.