Think about it. "Suppository." What a serene, classical sort of sound it has. It might be the name of a room of a cathedral, or the architectural term for some supporting part of a dome. Or perhaps a kind of garden pavilion, a pergola or gazebo...
"Have you seen Lady Blanche?" the Duke asked testily. "By Jove, Mrs. Gleaning, she becomes flightier by the hour!"
"I have, Your Grace," replied the housekeeper slyly. "I believe she is with Sir Edgar in the Suppository."