ETYM Cf. French changeable.
1. Subject to change; SYN. uncertain, unsettled.
2. Such that alteration is possible; having a marked tendency to change; SYN. changeful.
3. Varying in color when seen in different lights or from different angles; SYN. chatoyant, iridescent, shot.

Having unpredictable ups and downs.

ETYM Latin mutabilis, from mutare to change. Related to Move.
1. Capable of or tending to change in form or quality or nature; SYN. changeable.
2. Capable of being changed, especially for the worse; fickle.

ETYM Latin variabilis: cf. French variable.
1. Liable to or capable of change.
2. (Used of a device) Designed so that a property (as e.g. light) can be varied.

In a manner that changes, alterably

In a manner which is subject to mutation, changeably, variably

With variation; in a variable manner or to a variable degree.