hypogeum

From Latin hypogaeum, from Ancient Greek ὑπόγειον (hupógeion), a noun use of the neuter singular of ὑπόγειος (hupógeios, “underground”).

• (UK) IPA^(key): /hʌɪpəˈd͡ʒiːəm/, /hɪpəˈd͡ʒiːəm/

hypogeum (plural hypogeums or hypogea)

1. An underground room or cavern (also used figuratively).
   • 1969, JG Ballard, The Atrocity Exhibition:

     Contour: the unique parameters of Karen’s body – beckoning vents of mouth and vulva, the soft hypogeum of the anus.