adjective/aʁ.bi.tʁɛʁ/
arbitrary (determined by impulse)
“1864, Rudolf Charles, Preface to Testament by Jean Meslier, page 13” — An arbitrary act, condemned by all members, seems to me to have awakened this desire for revenge which for years killed all sympathetic feelings for us in the breast of the man in question.
Related: arbitrairement
Borrowed from Latin arbitrārius.