/fəˈnɒmɪnən; US -nɒn ||; fəˈnɑməˌnɑn/noun [C] (plural phenomena /-ɪnə ||; -ənə/) a fact or an event in nature or society, especially one that is not fully understood 现象: Acid rain is not a natural phenomenon. It is caused by pollution. 酸雨不是自然现象，而是由污染造成的。