In a way based on random choice or personal whim rather than reason, system, or fairness; without following rules or logic.
From Latin 'arbitrarius,' meaning 'depending on the will.' An 'arbiter' or 'arbitrator' originally meant someone with complete power to decide, leading to the sense of randomness and personal judgment.
It's fascinating that 'arbitrary' comes from 'arbiter'—meaning someone with absolute power—because it reveals that absolute power always seemed random and unreasonable to those under it, which is why the word took on such a negative meaning.
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