Lewis & Short

index, dĭcis, com. [1. indico], he who (that which) points out, a pointer, indicator (class.).

  1. I. Lit.
    1. A. Of things.
      1. 1. Of the forefinger, index-finger.
          1. (α) With digitus: indice monstraret digito, Hor. S. 2, 8, 26; Isid. Orig. 11, 1, 70.
          2. (β) Alone: sed plane pollex, non index, Cic. Att. 13, 46, 1.
      2. 2. In gen., an index, sign, mark, indication, proof: complexus, summae benevolentiae falsi indices in amore simulato, Cic. Phil. 11, 2, 5: quia continetis vocem, indicem stultitiae vestrae, id. Rab. Perd. 6, 18: auctoris anulus index, Ov. P. 2, 10, 3: lacrimas paenitentiae indices profuderunt, Curt. 5, 10, 13: herbae horarum indices heliotropium ac lupinum, Plin. 18, 27, 67, § 252: imago animi vultus, indices oculi, Cic. Or. 18, 60: Janum indicem pacis bellique fecit, Liv. 1, 19, 2.
    2. B. Of persons.
      1. 1. In gen., one who indicates or discloses, a discoverer, director, guide, informer, discloser, witness: haec omnia indices detulerunt, rei confessi sunt, Cic. Cat. 4, 3, 5: Sestius ab indice Cn. Nerio de ambitu est postulatus, id. Q. Fr. 2, 3, 5; id. Clu. 7, 21: immittere ad rei probationem, Just. 32, 2 fin.: idem et testis, Tac. A. 4, 28.
      2. 2. Esp., in a bad sense, an informer, betrayer, spy: Catilinam vallatum indicibus atque sicariis, Cic. Mur. 24, 49: saeptus armatis indicibus, id. Sest. 44, 95; id. Vat. 10, 24.
  2. II. Transf.
    1. A. Of books.
      1. 1. A title, superscription: deceptus indicibus librorum, Cic. de Or. 2, 14, 61: alteri (libello) Gladius, alteri Pugio index erat, Suet. Cal. 49: index orationis P. Scipionis nomen M. Naevii habet, Liv. 38, 56.
      2. 2. An index, catalogue, table, list, summary: ut non indicem certe ex bibliotheca sumptum transferre in libros suos possit, Quint. 10, 1, 57: philosophorum, Sen. Ep. 39, 2; cf. Gell. 3, 3, 1: hactenus omnia jura quasi per indicem tetigisse satis est, Gai. Inst. 3, 54: quasi per indicem rem exponere, id. ib. 4, 15: fungar indicis partibus, Plin. Ep. 3, 5, 2.
    2. B. Of paintings or statues, an inscription: nec quaeris, quid quaque index sub imagine dicat, Tib. 4, 1, 30: tabula in aedem Matris Matutae cum indice hoc posita est, etc., Liv. 41, 28, 8.
    3. C. Of a touchstone: in durum silicem, qui nunc quoque dicitur Index, Ov. M. 2, 706.