The Oxford Thesaurus An A-Z Dictionary of Synonyms - changeableadj.

1) variable, mutable, protean, inconstant, unstable, unsettled, shifting, uncertain, irregular, uneven, unpredictable, labile, capricious, erratic, fickle, unreliable, undependable, mercurial, volatile: The weather has been changeable for the past week. 2) alterable, modifiable, transformable, convertible: Their meeting-places were changeable and known only to them.