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]

The Collaborative International Dictionary of English v.0.48:

Overpass \O`ver*pass"\, v. i.
   To pass over, away, or off.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

overpass \o"ver*pass`\, n.
   A road or other pathway which passes over another road,
   railroad, or other path; as, he stopped on the street under
   the railroad overpass.
   [PJC]

The Collaborative International Dictionary of English v.0.48:

Overpass \O`ver*pass"\, v. t. [imp. & p. p. Overpassed; p. pr.
   & vb. n. Overpassing.] [Cf. Surpass.]
   [1913 Webster]
   1. To go over or beyond; to cross; as, to overpass a river;
      to overpass limits.
      [1913 Webster]

   2. To pass above; -- of roadways and other paths; as, the
      highway overpasses the railroad tracks.
      [PJC]

   3. To pass over; to omit; to overlook; to disregard.
      [1913 Webster]

            All the beauties of the East
            He slightly viewed and slightly overpassed.
                                                  --Milton.
      [1913 Webster]

   4. To surpass; to excel. [R.] --R. Browning.
      [1913 Webster]

WordNet (r) 3.0 (2006):

overpass
    n 1: bridge formed by the upper level of a crossing of two
         highways at different levels [syn: overpass, flyover]