1. Based on random choice or personal whim, rather than any reason or system
The decision seemed arbitrary and unfair.
A decisão pareceu arbitrária e injusta.
2. Despotic or tyrannical; characterized by absolute power exercised without restraint
The arbitrário ruler made decisions without consulting anyone.
O governante arbitrário tomava decisões sem consultar ninguém.
3. Selected at random without a specific reason or principle
They chose an arbitrary number for the experiment.
Eles escolheram um número arbitrário para o experimento.