The Collaborative International Dictionary of English v.0.48:

Colonnade \Col`on*nade"\, n. [F. colonnade, It. colonnata, fr.
   colonna column. See Colonel.] (Arch.)
   A series or range of columns placed at regular intervals with
   all the adjuncts, as entablature, stylobate, roof, etc.
   [1913 Webster]

   Note: When in front of a building, it is called a portico;
         when surrounding a building or an open court or square,
         a peristyle.
         [1913 Webster]

WordNet (r) 3.0 (2006):

colonnade
    n 1: structure consisting of a row of evenly spaced columns
    2: a structure composed of a series of arches supported by
       columns [syn: arcade, colonnade]

Moby Thesaurus II by Grady Ward, 1.0:

82 Moby Thesaurus words for "colonnade":
   access, aisle, alley, ambulatory, aperture, arcade, areaway,
   artery, atlas, avenue, baluster, balustrade, banister, base,
   breezeway, caryatid, channel, cloister, colonnette, column,
   communication, conduit, connection, corridor, covered way, dado,
   defile, die, exit, ferry, footstalk, ford, gallery, hall, hallway,
   inlet, interchange, intersection, jack, junction, lane, loggia,
   newel-post, opening, outlet, overpass, pass, passage, passageway,
   pedestal, pedicel, peduncle, pergola, peristyle, pier, pilaster,
   pile, piling, pillar, plinth, pole, portico, post, queen-post,
   railroad tunnel, shaft, socle, staff, stalk, stanchion, stand,
   standard, stem, subbase, surbase, telamon, traject, trajet, trunk,
   tunnel, underpass, upright