Lewis & Short

conjectĭo, ōnis, f. [conicio] (very rare), a hurling, throwing.

  1. I. Prop.: telorum, Cic. Caecin. 15, 43.
  2. II. Trop.
    1. A. A putting together, comparing: annonae et aestimationis, Cic. Verr. 2, 3, 82, § 189 (Ernesti, coauctio; Zumpt, conjunctio).
    2. B. Meton.
      1. 1. (Acc. to conicio, I. B. 2.) An inference, conjecture, interpretation (for conjectura): somniorum, Cic. Div. 2, 63, 130: conjectionem fieri ejus, quod reliquit, Dig. 28, 1, 21.
      2. 2. Conjectio causae, the draft, summary, or outline of a law-case, Gai Inst. 4, 15; Dig. 50, 17, 1; cf. Ps.-Ascon. ap. Cic. Verr. 2, 1, 9, § 26 (p. 164 Orell.).
        Hence,
      3. * 3. In gen., a controverted question, subject of a controversy, Plin. 28, 2, 3, § 13.