quicksilver
adj : 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" [syn: {erratic}, {fickle}, {mercurial},
{quicksilver(a)}]
n : a heavy silvery toxic univalent and bivalent metallic
element; the only metal that is liquid at ordinary
temperatures [syn: {mercury}, {Hg}, {atomic number 80}]