pentad

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

用法提示：pentad作为名词，表示由五个事物组成的集合或五元组。

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

用法提示：pentad作为名词，表示五价物或五个一组的概念。

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

用法提示：pentad作为名词，表示五年的时段。