un·der·croft 
(ŭndər-krôft′, -krŏft′)
(ŭndər-krôft′, -krŏft′)n.
A crypt, especially one used for burial under a church.
[Middle English : under-, under- + croft, crypt (from Middle Dutch crofte, from Medieval Latin crupta, from Latin crypta, crypt; see CRYPT).]