Lewis & Short

circŭlus, i, m. (contr. circlus, like vinclum = vinculum, Verg. G. 3, 166) [kindred with κίρκος, κύκλος, circinus],

  1. I. a circular figure, a circle: circulus aut orbis, qui κύκλος Graece dicitur, Cic. N. D. 2, 18, 47: muri exterior, Liv. 36, 9, 12: circulus ad speciem caelestis arcūs orbem solis ambiit, Suet. Aug. 95.
    1. B. Esp.
      1. 1. In astronomy, a circular course, orbit: stellae circulos suos orbesque conficiunt celeritate mirabili, Cic. Rep. 6, 15, 15: aequinoctialis, solstitialis, septentrionalis, Varr. L. L. 9, § 24; Ov. M. 2, 516: lacteus, the Milky Way, Plin. 2, 25, 23, § 91; 18, 29, 69, § 230: signifer, Vitr. 6, 1, 1; 9, 8, 8.
      2. 2. In geog., a zone or belt of the eartb’s surface: plura sunt segmenta mundi, quae nostri circulos appellavere, Graeci parallelos, Plin. 6, 34, 39, § 212 sqq.
    2. C. Trop., of time: mensis artiore praecingitur circulo, Sen. Ep. 12, 6.
  2. II. Meton.
    1. A. Any circular body; a ring, necklace, hoop, chain, Verg. A. 5, 559; 10, 138; id. G. 3, 166; Plin. 14, 21, 27, § 132; Suet. Aug 80.
    2. B. A circle or company for social intercourse (very freq.): in conviviis rodunt, in circulis vellicant, Cic. Balb. 26, 57; so with convivia also, Liv. 32, 20, 3; 34, 61, 5; 44, 22, 8; Domit. Mars. ap. Quint. 6, 3, 105; Tac. A. 3, 54; Nep. Epam. 3, 3; Mart. 2, 86, 11; 10, 62, 5: cir culos aliquos et sessiunculas consectarl, Cic. Fin. 5, 20, 56 per fora et circulos locuti sunt, Tac Agr 43; cf Quint. 12, 10, 74: quemcumque patrem familias arripuissetis ex aliquo circulo, Cic. de Or. 1, 34, 159; 1, 38, 174: de circulo se subducere, to withdraw from the assembly, id. Q. Fr. 3, 4, 1; Quint. 2, 12 10; cf.: densa circumstantium corona latissimum judicium multiplici circulo ambibat, Plin. Ep 6, 33, 3.