Lewis & Short

rŏtundĭtas, ātis,f. [rotundus], a round shape, roundness, rotundity (post-Aug.).

  1. I. Lit.: gemma rotunditatis absolutae, Plin. 37, 11, 73, § 190; so id. 18, 13, 34, § 130; 16, 23, 35, § 86; 19, 5, 25, § 76 al.
  2. II. Trop.: verborum, a roundness, smoothness, Macr. S. 7, 5: Symmachi, Sid. Ep. 1, 1.
    Concr., a circular space: rotunditas dimidii cubiti, Vulg. 3 Reg. 7, 35.