four-leaf clover
noun [ C ] uk/ˌfɔː.liːf ˈkləʊ.vər/ us/ˌfɔːr.liːf ˈkloʊ.vɚ/ (also four-leaved clover, /ˌfɔː.liːvd ˈkləʊ.vər/ /ˌfɔːr.liːvd ˈkloʊ.vɚ/)
四叶苜蓿，四叶草（据信能给发现者带来好运）
a clover (= a small plant) with a leaf that is divided into four parts rather than the usual three, thought to bring good luck to anyone who finds it