Indices is one plural of index, taken from Latin. English also has indexes. Which one you see depends on the meaning and how formal the writer is.

Indices is one plural of indexindices 是 index 的其中一種複數形， taken from Latin是從拉丁文來的。 English also has indexes英文也有 indexes 這個複數形。 Which one you see depends on the meaning and how formal the writer is用哪一個要看意思，還有寫的人多正式。

When index means a number that tracks prices, shares, or some other measure (price indices, stock indices), writers in economics, science, and maths often prefer indices. When index means the list at the back of a book, indexes is now the usual plural. In maths, index can also mean a small number written up or down beside another (a power, or a mark that says “which one”); those too are often called indices.

When index means a number that tracks prices, shares, or some other measure當 index 是指追蹤股價、物價之類的一個數字時， (price indices, stock indices)（像 price indices 物價指數、stock indices 股票指數）， writers in economics, science, and maths often prefer indices經濟、科學、數學領域的寫作常會用 indices。 When index means the list at the back of a book當 index 是指書後面的索引時， indexes is now the usual plural現在通常會用 indexes 這個複數形。 In maths, index can also mean a small number written up or down beside another在數學裡，index 也可以指寫在另一個數字旁邊、上面或下面的小數字， (a power, or a mark that says "which one")（像次方，或用來標示「是哪一個」的記號）， those too are often called indices這些也常常被稱作 indices。

Say IN-di-seez. Using indices for a book’s back-of-the-book lists is not wrong, but it can sound stiff.

Say IN-di-seez讀作 IN-di-seez。 Using indices for a book's back-of-the-book lists is not wrong用 indices 來指書後面的索引並不算錯， but it can sound stiff但可能會聽起來有點生硬。