Meaning : Marked by erratic changeableness in affections or attachments.
Example :
Fickle friends.
A flirt's volatile affections.
Synonyms : volatile
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 : erratic, mercurial, quicksilver