Not fixed or firm; liable to change; unstable; of a changeable mind; not firm in opinion or purpose; inconstant; capricious; as, Fortune's fickle wheel.
source: Webster 1913
adjective satellite
marked by erratic changeableness in affections or attachments
Fickle friends. A flirt's volatile affections.
source: WordNet 3.0
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.
