Lewis & Short

dū̆plĭcātĭo, ōnis, f. [duplico],

  1. I. a doubling (post-Aug.): radiorum, i. e. reflection, Sen. Q. N. 4, 8; Dig. 9, 4, 31: temporis, ib. 48, 19, 8.
  2. II. Esp.,
          1. (α) As arithm. t. t., a doubling, multiplication by two, Mart. Cap. 7, § 750.
          2. (β) As jurid. t. t., the answering of one objection by another, turning an objection upon an adversary, Gai. 4, 127.
          3. (γ) As rhet. fig., = ἀναδίπλωσις, the repetition of a word in beginning a clause, Ruf. Schem. Lex. § 8.