• WordNet 3.6
    • n hexad the cardinal number that is the sum of five and one
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Webster's Revised Unabridged Dictionary
    • n Hexad (chem) An atom whose valence is six, and which can be theoretically combined with, substituted for, or replaced by, six monad atoms or radicals; as, sulphur is a hexad in sulphuric acid. Also used as an adjective.
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Century Dictionary and Cyclopedia
    • n hexad The sum of six units; the number six; also, a series of six numbers.
    • n hexad In chem., an element the atoms of which have six times the saturating power or equivalence of the hydrogen atom, as sulphur in certain conditions.
    • n hexad Also spelled hexade.
    • n hexad A hexagon.
    • hexad Having a combining power equivalent to six times that of hydrogen. Same as hexavalent and sexivalent.
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Chambers's Twentieth Century Dictionary
    • n Hexad hek′sad a series of six numbers:
    • n Hexad hek′sad (chem.) an element or radical with the combining power of six units—i.e. of six atoms of hydrogen.
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Webster's Revised Unabridged Dictionary
L. hexas, hexadis, the number six, Gr. , , fr. "e`x six


In literature:

Intersecting in the hexad axis are six planes of symmetry of two kinds, and perpendicular to them is an equatorial plane of symmetry.
"Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7" by Various