pentad

[ pen-tad ]

noun

1. a period of five years.
2. a group of five.
3. the number five.
4. Chemistry. a pentavalent element or group.
5. Climatology. a period of five consecutive days.

pentad

/ ˈpɛntæd /

noun

1. a group or series of five
2. the number or sum of five
3. a period of five years
4. chem a pentavalent element, atom, or radical
5. meteorol a period of five days

Word History and Origins

Origin of pentad¹

First recorded in 1645–55; from Greek pentad- (stem of pentás ) group of five; pent-, -ad ¹

Word History and Origins

Origin of pentad¹

C17: from Greek pentas group of five

Example Sentences

Nitrogen in the triad condition in the amines is far less poisonous than in the pentad condition.

From Project Gutenberg

There is something to be said for this view, but on the whole the balance of the evidence is in favor of nitrogen being a pentad.

From Project Gutenberg

The structure of Aristotle's Pentad for five act plays is useful as a framework for solving personal problems.

From Project Gutenberg

But this oddness belongs to other numbers also (pentad, heptad, &c.).

From Project Gutenberg

Five, or the pentad, is everything; it stops the power of poisons, and is dreaded by evil spirits.

From Project Gutenberg