permutation
/ˌpɜːmjʊˈteɪʃən/noun
1- a way, especially one of several possible variations, in which a set or number of things can be ordered or arranged变化组合：
his thoughts raced ahead to fifty different permutations of what he must do.
就必须要做的事他很快想出了50种不同的变化组合。
1.1
- mass noun Mathematics the action of changing the arrangement, especially the linear order, of a set of items【数】排列; 置换。
1.2
- Brit. a selection of a specified number of matches in a football pool〈英〉（足球普尔中特定比赛场次的）挑选。
派生词
permutational
adjective词源
late Middle English （in the sense 'exchange, barter'）： via Old French from Latin permutatio（n-）, from the verb permutare 'change completely' （see PERMUTE）.