pentad

Synonym of quinquennium: a five-year period, especially in reference to the first and second halves of calendrical decades.

A five-day period, especially a temperature average taken every five days.

A five-day division of the Chinese calendar, forming part of a solar term (Chinese: 候).

A pentavalent element or group: an atom or molecule with a valence of five, comparable with five atoms of hydrogen.