The Collaborative International Dictionary of English v.0.48:

Rampant \Ramp"ant\ (r[a^]mp"ant), a. [F., p. pr. of ramper to
   creep. See Ramp, v.]
   1. Ramping; leaping; springing; rearing upon the hind legs;
      hence, raging; furious.
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            The fierce lion in his kind
            Which goeth rampant after his prey.   --Gower.
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            [The] lion . . . rampant shakes his brinded mane.
                                                  --Milton.
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   2. Ascending; climbing; rank in growth; exuberant.
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            The rampant stalk is of unusual altitude. --I.
                                                  Taylor.
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   3. (Her.) Rising with fore paws in the air as if attacking;
      -- said of a beast of prey, especially a lion. The right
      fore leg and right hind leg should be raised higher than
      the left.
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   Rampant arch.
      (a) An arch which has one abutment higher than the other.
      (b) Same as Rampant vault, below.

   Rampant gardant (Her.), rampant, but with the face turned
      to the front.

   Rampant regardant, rampant, but looking backward.

   Rampant vault (Arch.), a continuous wagon vault, or cradle
      vault, whose two abutments are located on an inclined
      plane, such as the vault supporting a stairway, or forming
      the ceiling of a stairway.
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The Collaborative International Dictionary of English v.0.48:

Vault \Vault\ (v[add]lt; see Note, below), n. [OE. voute, OF.
   voute, volte, F. vo[^u]te, LL. volta, for voluta, volutio,
   fr. L. volvere, volutum, to roll, to turn about. See
   Voluble, and cf. Vault a leap, Volt a turn, Volute.]
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   1. (Arch.) An arched structure of masonry, forming a ceiling
      or canopy.
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            The long-drawn aisle and fretted vault. --Gray.
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   2. An arched apartment; especially, a subterranean room, used
      for storing articles, for a prison, for interment, or the
      like; a cell; a cellar. "Charnel vaults." --Milton.
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            The silent vaults of death.           --Sandys.
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            To banish rats that haunt our vault.  --Swift.
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   3. The canopy of heaven; the sky.
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            That heaven's vault should crack.     --Shak.
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   4. [F. volte, It. volta, originally, a turn, and the same
      word as volta an arch. See the Etymology above.] A leap or
      bound. Specifically:
      (a) (Man.) The bound or leap of a horse; a curvet.
      (b) A leap by aid of the hands, or of a pole, springboard,
          or the like.
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   Note: The l in this word was formerly often suppressed in
         pronunciation.
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   Barrel vault, Cradle vault, Cylindrical vault, or
   Wagon vault (Arch.), a kind of vault having two parallel
      abutments, and the same section or profile at all points.
      It may be rampant, as over a staircase (see Rampant
      vault, under Rampant), or curved in plan, as around the
      apse of a church.

   Coved vault. (Arch.) See under 1st Cove, v. t.

   Groined vault (Arch.), a vault having groins, that is, one
      in which different cylindrical surfaces intersect one
      another, as distinguished from a barrel, or wagon, vault.


   Rampant vault. (Arch.) See under Rampant.

   Ribbed vault (Arch.), a vault differing from others in
      having solid ribs which bear the weight of the vaulted
      surface. True Gothic vaults are of this character.

   Vault light, a partly glazed plate inserted in a pavement
      or ceiling to admit light to a vault below.
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