The Collaborative International Dictionary of English v.0.48:

Conduit \Con"duit\ (? or ?; 277), n. [F., fr. LL. conductus
   escort, conduit. See Conduct.]
   1. A pipe, canal, channel, or passage for conveying water or
      fluid.
      [1913 Webster]

            All the conduits of my blood froze up. --Shak.
      [1913 Webster]

            This is the fountain of all those bitter waters, of
            which, through a hundred different conduits, we have
            drunk.                                --Burke.
      [1913 Webster]

   2. (Arch.)
      (a) A structure forming a reservoir for water. --Oxf.
          Gloss.
      (b) A narrow passage for private communication.
          [1913 Webster] Conduit system

WordNet (r) 3.0 (2006):

conduit
    n 1: a passage (a pipe or tunnel) through which water or
         electric wires can pass; "the computers were connected
         through a system of conduits"

Moby Thesaurus II by Grady Ward, 1.0:

52 Moby Thesaurus words for "conduit":
   access, adit, aisle, alley, ambulatory, aperture, aqueduct, arcade,
   artery, avenue, canal, channel, cloister, colonnade, communication,
   connection, corridor, course, covered way, defile, ditch, duct,
   egress, entrance, exit, ferry, ford, gallery, ingress, inlet,
   interchange, intersection, junction, lane, opening, outlet,
   overpass, pass, passage, passageway, portico, railroad tunnel,
   traject, trajet, trench, trough, troughing, troughway, tunnel,
   underpass, watercourse, way



Easton's 1897 Bible Dictionary:

Conduit
   a water-course or channel (Job 38:25). The "conduit of the upper
   pool" (Isa. 7:3) was formed by Hezekiah for the purpose of
   conveying the waters from the upper pool in the valley of Gihon
   to the west side of the city of David (2 Kings 18:17; 20:20; 2
   Chr. 32:30). In carrying out this work he stopped "the waters of
   the fountains which were without the city" i.e., "the upper
   water-course of Gihon", and conveyed it down from the west
   through a canal into the city, so that in case of a siege the
   inhabitants of the city might have a supply of water, which
   would thus be withdrawn from the enemy. (See SILOAM.)

     There are also the remains of a conduit which conducted water
   from the so-called "Pools of Solomon," beyond Bethlehem, into
   the city. Water is still conveyed into the city from the
   fountains which supplied these pools by a channel which crosses
   the valley of Hinnom.