permutation
noun uk/ˌpɜː.mjuːˈteɪ.ʃən/ us/ˌpɝː.mjuːˈteɪ.ʃən/
(DIFFERENT WAY/FORM)
[ C usually plural ] formal（数学的）排列，置换
any of the various ways in which a set of things can be ordered
There are 120 permutations of the numbers 1, 2, 3, 4 and 5: for example, 1, 3, 2, 4, 5 or 5, 1, 4, 2, 3. 数字1、2、3、4、5有120种排列方式，如1、3、2、4、5和5、1、4、2、3。
He made 16 separate applications for tickets using various permutations of his children's names. 使用自己孩子名字的各种形式，他分别16次申请票证。
[ C ]（几种中的）一种
one of several different forms
The company has had five different names in its various permutations over the last few years. 在过去几年里，该公司用不同形式使用过5个不同的名字。