An element of a set that when added to any other element in the set produces a sum identical with the element to which it is added.

零元素：集合中的一个元素，当它加上集合中的任何一个元素时，得到的数值等于被加元素值。

youdao

This was the Rooney that Capello will have wanted to see after a red card in Manchester United's defeat at Fulham prompted the England coach to label his striker "a crazy man" - with no tantrums at Wembley, only an exhibition of the gifts that make him such a vital element of the international set-up.

BBC: England 4-0 Slovakia

In practice, that element of a post-independence referendum is set aside.

BBC: Royal role in independence debate

Garcia-Lopez finally found an element of consistency at the beginning of the third set and had Murray scampering all over the court to retrieve a series of well-placed groundstrokes.

BBC: Australian Open: Andy Murray crushes Garcia-Lopez