a very large amount of something, especially a larger amount than you need, want, or can deal with

There's a plethora of books about the royal family. 有关皇室的书非常多。

The plethora of regulations is both contradictory and confusing. 过多的规章制度既相互矛盾又令人迷惑。

Synonym: profusion

Compare: cornucopia an embarrassment of riches