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A group of five.

[Greek pentas, pentad-, group of five, from pente, five; see penkwe in Indo-European roots.]


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]


(ˈpɛn tæd)

1. a period of five years.
2. a group of five.
3. the number five.
4. a pentavalent element or group.
[1645–55; < Greek pentad- (s. of pentás) group of five. See pent-, -ad1]


 a group of five, especially five years, 1880.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.pentad - the cardinal number that is the sum of four and onepentad - the cardinal number that is the sum of four and one
digit, figure - one of the elements that collectively form a system of numeration; "0 and 1 are digits"
References in periodicals archive ?
The light and colored pentads of Clifford's set of such rank contain in threes 2-diagonal matrices, corresponding to 3 space coordinates in accordance with Dirac's equation.
After applying a filter to our dataset to exclude all incomplete pentads (i.
The output of the model was also grouped in pentads for the present rainy period (AJ run [Figure 15b]) and the future rainy period (AK run [Figure 15c]).
The syndiotacticity level of sPP was characterized by the content of racemic pentads concluded from [C.
The continuing controversy about the significance of the boundaries between Livy's pentads and decads is a warning that this kind of question invites very subjective responses.
For each studied age, the 10 tree-ring pentads were ground together and one [[Delta].
Gust says his group is already using the pentads to study natural photosynthesis.
min] anomalies of 9 nonoverlapping pentads from the coldest period in the climatology (1 January to 15 February) from the 525 histALL and histNAT runs were calculated and fitted to probability distribution functions (PDFs).
There exist only six Clifford pentads (for instance, [5, 6]): I call one of them (the pentad [beta] the light pentad, three ([xi], [eta], [theta])--the chromatic pentads, and two ([DELTA], [GAMMA])--the gustatory pentads.
The analysis of the carbonyl carbon resonances is interesting because of the sensitivity of this group to the stereochemical configuration of surrounding units in terms of pentads for the OM-HEMA system.