定さだめない

i-adjective

uncertain; transient; changeable

Describes something that cannot be fixed or relied upon; often used for life, the world, or fate. Literary and somewhat old-fashioned.

• 世よの中なかは定さだめないものだ。

  The world is an uncertain place.

• 人ひとの心こころは定さだめない。

  People's hearts are changeable.