The Collaborative International Dictionary of English v.0.48:

Reconnoiter \Rec`on*noi"ter\, Reconnoitre \Rec`on*noi"tre\
   (r?k`?n*noi"t?r), v. t. [F. reconnoitre, a former spelling of
   reconna[^i]tre. See Recognize.]
   1. To examine with the eye to make a preliminary examination
      or survey of; esp., to survey with a view to military or
      engineering operations.
      [1913 Webster]

   2. To recognize. [Obs.] --Sir H. Walpole.
      [1913 Webster]

WordNet (r) 3.0 (2006):

reconnoiter
    v 1: explore, often with the goal of finding something or
         somebody [syn: scout, reconnoiter, reconnoitre]

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "reconnoiter":
   be vigilant, be watchful, bug, case, course, cover, do, eye,
   eyeball, follow, gaze at, go over, have a looksee, hold in view,
   keep in sight, keep in view, keep under observation, look after,
   look at, look on, look upon, make a reconnaissance, measure,
   observe, overpass, pass over, pass through, patrol, peep,
   perambulate, peregrinate, pererrate, play the spy, ply, probe,
   put under surveillance, range, range over, regard, scour,
   scour the country, scout, scout out, spy, spy out, spy upon,
   stake out, sweep, track, transit, travel over, travel through,
   traverse, view, voyage, watch