catacomb

/ˈkatəkuːm/

IPA: /K AE1 T AH0 K OW0 M/

noun
  1. 1

    (often plural) An underground system of tunnels and chambers with recesses for graves, used (in former times) as a cemetery; a tunnel system used for burying the dead, as in Paris or Ancient Rome.

Source: https://en.wiktionary.org/wiki/catacomb