1. two barrel vaults intersecting at right angles
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.]
1. (Arch.) An arched structure of masonry, forming a ceiling
The long-drawn aisle and fretted vault. --Gray.
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.
The silent vaults of death. --Sandys.
To banish rats that haunt our vault. --Swift.
3. The canopy of heaven; the sky.
That heaven's vault should crack. --Shak.
4. [F. volte, It. volta, originally, a turn, and the same
word as volta an arch. See the Etymology above.] A leap or
(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.
Note: The l in this word was formerly often suppressed in
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.
WordNet (r) 3.0 (2006):
n 1: two barrel vaults intersecting at right angles