[SUB- 7 b.] A subordinate group; a subdivision of a group. (Chiefly Nat. Hist.)

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1845.  Darwin, Voy. Nat., xvii. 379. One species of the sub-group Cactornis. Ibid. (1859), Orig. Spec., iv. 126. Small and broken groups and sub-groups will finally tend to disappear.

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1899.  Allbutt’s Syst. Med., viii. 772. The first three classes might be included in one group—Alopecia neurotica, with sub-groups universalis, localis, and circumscripta.

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  b.  Math. A series of operations forming part of a larger group.

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1888.  G. G. Morrice, trans. F. Klein’s Lect. Ikosahedron, 6. The simplest sub-group … is always that which arises from the repetitions of an individual operation.

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1892.  F. N. Cole, trans. Netto’s Th. Substitutions, 41. No two of these a subgroups have any element in common.

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