changeable; volatile; fickle; flighty; erratic

a mercurial nature.

animated; lively; sprightly; quick-witted.

pertaining to, containing, or caused by the metal mercury.

( initial capital letter ) of or pertaining to the god Mercury.

( initial capital letter ) of or pertaining to the planet Mercury.

Pharmacology . a preparation of mercury used as a drug.

adjective

calm , tranquil , unchangeable , unperturbable , unvarying

adjective

blowing hot and cold , bubbleheaded , buoyant , capricious , changeable , effervescent , elastic , erratic , expansive , fickle , flaky , flip * , fluctuating , gaga , gay , impulsive , inconstant , irregular , irrepressible , lighthearted , lively , lubricious , mad , mobile , movable , quicksilver , resilient , short-fuse , spirited , sprightly , ticklish , unpredictable , unstable , up-and-down * , variable , volatile , yo-yo , fantastic , fantastical , freakish , inconsistent , temperamental , uncertain , unsteady , whimsical , adroit , clever , cunning , flighty , quick , shrewd