Lewis & Short

explōrātor, ōris, m. [exploro], a searcher out, examiner, explorer; a prying person, a spy (not in Cic.)

  1. I. In gen.: rerum, Lucil. ap. Non. 366, 31: suppositicius, Plaut. Ps. 4, 7, 71.
        1. b. Adj., searching: ignes, Claud. III. Cons. Hon. praef. 11: foci, Mart. 8, 51, 4.
  2. II. In partic.
    1. A. In milit. lang.
          1. (α) A spy, scout, Caes. B. G. 1, 12, 2; 2, 5, 4; 2, 11, 3; 2, 17, 1 et saep.
          2. (β) Plur., skirmishers, Tac. H. 2, 17; cf. Inscr. Orell. 5877 sqq.
    2. B. Explorator viae, one who ran before the emperor to clear the way, Suet. Tib. 60.