形容词

1. 武断的;任意的;任性的;主观的
If you describe an action, rule, or decision as arbitrary, you think that it is not based on any principle, plan, or system. It often seems unfair because of this.

1. based on or subject to individual discretion or preference or sometimes impulse or caprice

e.g. an arbitrary decision
the arbitrary rule of a dictator
an arbitrary penalty
of arbitrary size and shape
an arbitrary choice
arbitrary division of the group into halves