1. | [c] (理解问题或使事物完整的)必要的环节,不可缺少的一环something, such as a piece of information, that is necessary for sb to be able to understand a problem or in order to make sth complete |
2. | [sing] 缺环(推想中从类人猿发展到人类之间的过渡动物)an animal similar to humans that was once thought to exist at the time that apes were developing into humans |