mercurial
adjective
1. liable to sudden unpredictable change
- mercurial twists of temperament
Similar word(s): changeable, changeful, erratic, fickle, quicksilver
2. relating to or under the (astrological) influence of the planet Mercury
- the Mercurial canals
3. relating to or having characteristics (eloquence, shrewdness, swiftness, thievishness) attributed to the god Mercury
- more than Mercurial thievishness
4. relating to or containing or caused by mercury
- mercurial preparations
- mercurial sore mouth
noun
1. (obsolete) Any of the plants known as mercury. [13th-17th c.]
2. (astrology) Someone born under the influence of Mercury. [from 16th c.]
3. (now historical) A preparation of mercury, especially as a treatment for syphilis. [from 17th c.]