Lewis & Short

gĕmellus, a, um, adj. dim. [geminus], born at the same time, twin-born, twin- (mostly poet.; cf. geminus).

  1. I. Lit.
    1. A. Adj.: flebat avus Phoebeque soror fratresque gemelli, Ov. H. 8, 77: proles, id. ib. 6, 121; id. M. 9, 453: fetus, id. H. 6, 143: partus, id. M. 6, 712; Vulg. Cant. 4, 2.
    2. B. Subst.: gĕmellus, i, m., a twin: gemelle Castor et gemelle Castoris, Cat. 4, 27: namque est enixa gemellos, Ov. M. 11, 316; cf. Verg. E. 1, 14: hac in re scilicet una Multum dissimiles, at cetera paene gemelli Fraternis animis, etc., Hor. Ep. 1, 10, 3.
  2. II. Transf.
    1. A. In gen., paired, double: poma cohaerentia et gemella, Plin. 15, 14, 15, § 51: vites, that have two clusters on one stalk, id. 14, 2, 4, § 21 (for which: geminae vites, Col. 3, 2, 10): gemella legio, formed out of two legions, Caes. B. C. 3, 4, 1; cf. geminus, II. A.
    2. B. Resembling or like, as twins: par nobile fratrum, Nequitia et nugis pravorum et amore gemellum, Hor. S. 2, 3, 244: pinus, Mart. 10, 92, 3: uniones, id. 12, 49, 12.