• Webster's Revised Unabridged Dictionary
    • n Undercroft (Arch) A subterranean room of any kind; esp., one under a church (see Crypt), or one used as a chapel or for any sacred purpose.
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Century Dictionary and Cyclopedia
    • n undercroft Any vault or secret passage under ground.
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Chambers's Twentieth Century Dictionary
    • n Undercroft un′dėr-kroft a vault under the choir or chancel of a church: a vault or secret walk underground.
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Webster's Revised Unabridged Dictionary
Under, + Prov. E. croft, a vault; cf. OD. krochte, crypt, and E. crypt,


In literature:

It is above the Norman undercroft, previously mentioned.
"Bell's Cathedrals: The Cathedral Church of Durham" by J. E. Bygate
N Dormitory (undercroft destroyed about 1870).
"Bell's Cathedrals: The Priory Church of St. Bartholomew-the-Great, Smithfield" by George Worley
Nothing can exceed the ugliness of the new domed tower of the church of Belem, or of the upper story imposed on the long undercroft.
"Portuguese Architecture" by Walter Crum Watson
One, which is generally called a lantern, was till lately hung in the undercroft.
"Bell's Cathedrals: The Cathedral Church of Wells" by Percy Dearmer
Cardinal Morton desired to be buried near the image of Our Lady of the Undercroft, and his tomb is close by.
"Canterbury" by Canon Danks