Occurring or appearing irregularly from time to time, but not often.
Created for a specific occasion.
Acting in the indicated role from time to time.
Intended for use as the occasion requires.
A person who does something only occasionally.
Unpredictable, erratic or fickle; mercurial.
The metal mercury.
An amalgam of mercury and tin applied to the backs of mirrors, quicksilvering.
To overlay with quicksilver.
To treat with quicksilver.