The Collaborative International Dictionary of English v.0.48:

flyover \flyover\ n.
   1. the upper level of a crossing of two highways at different
      levels; called in the United States an overpass; as, an
      overpass is called a flyover or a flypast in England.
      [Brit.]

   Syn: overpass, flypast.
        [WordNet 1.5]

   2. a low-altitude flight (usually of military aircraft) over
      spectators on the ground.

   Syn: flypast.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

flypast \fly"past\ (fl[imac]"p[a^]st), n.
   1. the upper level of a crossing of two highways at different
      levels; same as flyover; called in the United States an
      overpass. [Brit.]

   Syn: overpass, flyover.
        [WordNet 1.5]

   2. a low-altitude flight (usually of military aircraft) over
      spectators on the ground.

   Syn: flyover.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

flyover
    n 1: bridge formed by the upper level of a crossing of two
         highways at different levels [syn: overpass, flyover]
    2: a flight at a low altitude (usually of military aircraft)
       over spectators on the ground [syn: flyover, fly-by,
       flypast]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "flyover":
   Bifrost, bascule bridge, bateau bridge, bridge, cantilever bridge,
   caravan, carrefour, catwalk, cavalcade, cloverleaf, column,
   cortege, crossing, crosspoint, crossroad, crosswalk, crossway,
   drawbridge, dress parade, floating bridge, footbridge, funeral,
   gangboard, gangplank, gangway, grade crossing, intercrossing,
   intersection, level crossing, lift bridge, line, march past,
   motorcade, mule train, overbridge, overcrossing, overpass,
   pack train, parade, pomp, pontoon bridge, procession, promenade,
   review, rope bridge, rotary, skimmington, span, stepping-stone,
   stepstone, stream, string, suspension bridge, swing bridge,
   toll bridge, traffic circle, train, undercrossing, viaduct