pentad(redirected from pentads)
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A group of five.
1. (Mathematics) a group or series of five
2. (Mathematics) the number or sum of five
3. a period of five years
4. (Chemistry) chem a pentavalent element, atom, or radical
5. (Physical Geography) meteorol a period of five days
[C17: from Greek pentas group of five]
1. a period of five years.
2. a group of five.
3. the number five.
4. a pentavalent element or group.
Pentada group of five, especially five years, 1880.