pentad

The biologist identified a pentad of species that share a common ancestor.

生物学家鉴定出一个由五种物种组成的五元组，它们共享一个共同祖先。

In chemistry, a pentad often refers to a group of five atoms or bonds.

在化学中，五价基常指由五个原子或键组成的基团。

The meteor shower is expected to peak every pentad of years.

这场流星雨预计每五年达到一次高峰。