Meaning : Liable to sudden unpredictable change.
Example :
Erratic behavior.
Fickle weather.
Mercurial twists of temperament.
A quicksilver character, cool and willful at one moment, utterly fragile the next.
Synonyms : fickle, mercurial, quicksilver
Meaning : Likely to perform unpredictably.
Example :
Erratic winds are the bane of a sailor.
A temperamental motor; sometimes it would start and sometimes it wouldn't.
That beautiful but temperamental instrument the flute.
Synonyms : temperamental