Belle's serdab (pg. 161) -- A secret chamber in an ancient Eygptian tomb. In this case, Belle's garden shed love nest.
camarilla (pg. 216) -- A group of secret or confidential advisers.
elide (pg. 247) -- To omit or slur over.
parilka (pg. 261) -- A Russian steam room or sauna, with a cold plunge pool, part of a banya.