0 in a way that is based on chance rather than being planned or based on reason: --
1 in a way that uses personal power unfairly and without considering people's rights and wishes: --
Local officials enforce rules arbitrarily and unreasonably.
The clergy became a ruling class that arbitrarily made decrees affecting people's lives.
People have been held incommunicado for decades without trial and killed arbitrarily.
We didn't make these changes arbitrarily, but for a good reason.
You can't just arbitrarily say that there are going to be 500 more students.