Definition of "duodecad"

In forming triad systems in 15 letters, there are only four typical openings, viz: which, from the way in which the triads containing 1 are laced with those containing 2, may be called the single tetrad, triple tetrad, hexad, and duodecad types, ...

1919, National Academy of Sciences (U.S.), Memoirs of the National Academy of Sciences, page 73

Further generation was produced by addition and multiplication of the triad and quaternary to form a series of hebdomads and duodecads. By these computations, the Pythagorean 3 and 4 are directly generative of the astrological 7 and 11.

1938, Vincent Foster Hopper, Medieval Number Symbolism: Its Sources, Meaning, and Influence on Thought and Expression, Courier Corporation, page 53

Hopper points out that duodecads have been prominent in every ancient civilization and cites as examples twelve spokes in the wheel of the Hindu Rta, the twelve gates of hell where Egyptian Ra must spend the twelve hours of night, the twelve tribes of Israel, the twelve labors of Hercules, [...]

1972, Eleanor Webster Bulatkin, Structural Arithmetic Metaphor in the Oxford "Roland.", Ohio State University Press, page 10

Gnostic interpreters [...] found their notion that the final set of divinities within this thirty-fold Pleroma comprised a duodecad in Luke's reference to Jesus as a twelve-year-old in the temple; and they saw evidence of their doctrine that the twelfth aeon of the duodecad, Sophia, had fallen from the divine realm [...]

1996, Bart D. Ehrman, The Orthodox Corruption of Scripture: The Effect of Early Christological Controversies on the Text of the New Testament, Oxford University Press